Happy Days

With season four, Al Molinaro was added as Al Delvecchio, the new owner of Arnold's, after Pat Morita's character of Arnold moved on after his character got married. (Morita had left the program to star in a short-lived sitcom of his own, Mr. T and Tina, which was actually a spin-off of Welcome Back, Kotter. Morita also starred in a subsequent short-lived Happy Days spin-off series titled Blansky's Beauties.) Al Molinaro also played Al's twin brother Father Anthony Delvecchio, a Catholic priest. Al eventually married Chachi's mother (played by Ellen Travolta) and Father Delvecchio served in the wedding of Joanie to Chachi in the series finale.

The most major character changes occurred after season five with the addition of Scott Baio as Fonzie's cousin, Charles "Chachi" Arcola. Originally, the character Spike (mentioned as Fonzie's nephew in the episode "Not with My Sister You Don't", but also claimed to be his cousin, as was stated in one episode) was supposed to be the character who became Chachi. Season five also saw the introduction of more outlandish and bizarre plots including Fonzie making a bet with the Devil, and the appearance of Mork (Robin Williams), an alien who wanted to take Richie back to his homeworld. Although when first aired this ended with it all simply being a dream Richie was having, this episode was retconned in subsequent airings by way of additional footage to have actually taken place, with Mork having wiped everyone's memory except Richie's and then deciding to time travel to the present day (the setting of Mork & Mindy).

Lynda Goodfriend joined the cast as semi-regular character Lori Beth Allen, Richie's steady girlfriend, in season five, and became a permanent member of the cast between seasons eight and nine, after Lori Beth married Richie.

After Ron Howard (Richie) left the series in 1980, Ted McGinley joined the cast as Roger Phillips, the new physical education teacher at Jefferson High and nephew to Howard and Marion. He took over from the departed Richie Cunningham character, acting as counterpoint to Fonzie. Cathy Silvers also joined the cast as Jenny Piccolo, Joanie's best friend who was previously referenced in various episodes from earlier seasons and remained as a main cast member until the final season. Both actors were originally credited as guest stars but were promoted to the main cast during season ten after several series regulars left the show. The real focus of the series was now on the Joanie and Chachi characters, and often finding ways to incorporate Fonzie into them as a shoulder to cry on, advice-giver, and savior as needed. The Potsie character, who had already been spun off from the devious best friend of Richie to Ralph's best friend and confidant, held little grist for the writers in this new age, and was now most often used as the occasional "dumb" foil for punchlines (most often from Mr. C.—whom he later worked for at Cunningham Hardware—or Fonzie).

Billy Warlock joined the cast in season 10 as Roger's brother Flip, along with Crystal Bernard as Howard's niece K.C. They were intended as replacements for Erin Moran and Scott Baio (who departed for their own show, Joanie Loves Chachi) and were credited as part of the semi-regular cast. Both characters left with the return of Moran and Baio, following the cancellation of Joanie Loves Chachi. Al Molinaro also left Happy Days in season 10 for Joanie Loves Chachi. Pat Morita then returned to the cast as Arnold in his absence.

In season 11, the story line of Richie and Lori Beth is given closure with the two-part episode "Welcome Home". Richie returns home from the Army, but barely has time to unpack when he learns that his parents have lined up a job interview at The Milwaukee Journal for him. However, they are taken aback when he tells them he prefers to take his chances in California to become a Hollywood screenwriter. They remind him of his responsibilities and while Richie gives in, he becomes angry and discontented, torn between his obligations to his family and fulfilling his dream.

After a confrontation that ends with a conversation with Fonzie, he decides to face his family and declare his intentions. While somewhat reluctant at first, they support him and bid Richie, Lori Beth, and Little Richie an emotional farewell.

• Richie Cunningham – The protagonist for the first seven years of the series (1974–80). When Ron Howard left the show due to his burgeoning directorial career, Richie was written out by leaving to join the United States Army. He marries his girlfriend, Lori Beth, in season eight by phone, while Fonzie stands-in for him in the wedding.[9] Howard returned for guest appearances as Richie during the show's final season. He came back with Lori Beth and their son, Richie Jr., and Ralph in the season 11 two-part episode, "Welcome Home", and then left for California with Lori Beth and Richie Jr. to pursue a career in screenwriting. He also returned in "Passages", when he and his family attended Joanie and Chachi's wedding.[10]
• Marion Cunningham – Wife of Howard Cunningham, mother of Richie and Joanie, and a traditional homemaker. She is the only character who is allowed to call Fonzie by his real first name, Arthur, which she does affectionately.[11] She sometimes gets tired of being at home, such as in "Marion Rebels" where she gets into an argument with Howard and briefly gets a job as a waitress at Arnold's.[12] In "Empty Nest" when Joanie left for Chicago to pursue her music career, Marion had "empty nest syndrome" and was thrilled when her and Howard's niece, K.C., moved in with them.[13] Marion was one of only four characters to remain with the show throughout its entire run.
• Howard Cunningham – Husband of Marion Cunningham, father of Richie and Joanie, business owner of a hardware store called "Cunningham's Hardware", he is a lodge member, and family man. Frequently seen reading the daily newspaper in his easy chair.[1] Enjoys driving his beloved 1948 DeSoto Suburban. In "Letting Go", he did not want Joanie to go to Chicago, still seeing her as his "little girl". But after talking with Fonzie and realizing how much she has grown up, he supports her going.[14] In "Passages", Howard says that he is proud of Richie and Joanie in Joanie and Chachi's wedding. Howard is one of only two characters (the other being Fonzie) to appear in every episode of the series.
• Joanie Cunningham – Richie's younger sister. In early seasons, she is sometimes snooping on Richie's activities and would occasionally be sent to her room by her parents. She is affectionately called "Shortcake" by Fonzie. Later on, Joanie briefly joins a motorcycle gang after going on a date with a boy, whom she considered to be "dull". In "Smokin' Ain't Cool", Joanie started smoking in order to be in a cool club, until Fonzie sets her straight. For years, Fonzie's cousin, Chachi, had been chasing her until she eventually agreed to a date with him. She and Chachi would eventually form a band together; and in "Letting Go", they leave for Chicago to pursue their music career (which spun off the short-lived series Joanie Loves Chachi). Joanie, however, eventually left the band to return home to pursue a teaching career.[15] She and Chachi then broke up for a time until Chachi proposes to her and they get married in the series finale.
• Arthur Herbert Fonzarelli, a.k.a. The Fonz or Fonzie – Initially a minor character, he was a hugely popular breakout character and was made a series regular. Fonzarelli's "Fonzie" nickname and comeback phrase, "Sit on it," were created by the show's producer, Bob Brunner.[16][17][18] Known for being especially cool and for his catchphrases "(H)eyyyy!" and "Whoa!" His coolness gave him special powers, such as making machinery (such as Arnold's jukebox and other vending machines, electric lights, and car engines) function by pounding on them with his fist, or getting the attention of girls by snapping his fingers. His parents abandoned him as a child and his grandmother raised him from the age of four.
• Potsie Weber – Richie's best friend and an aspiring talented singer. He is somewhat more carefree and worldly than Richie in early seasons, then in mid-seasons, he becomes more often paired with Ralph for plots, and the two became inseparable. In later seasons, his character evolves to increasingly emphasize his dimwitted side, and Ralph would often say to him "You're such a Potsie". Potsie often lightheartedly mentioned the supposed hatred his father (who never appeared on the show) had for him. Potsie remained with the show after Richie and Ralph joined the Army; however, he was seen less frequently. While Potsie's character became underdeveloped in these later episodes (and he, along with Ralph, was one of the few characters absent from the finale), he is mentioned to regularly bowl with the Cunninghams and still continues his position as assistant manager of Cunningham Hardware, and as pledge master of the Leopard Lodge.
• Ralph Malph – In the first season, Ralph was more of a side character to plots, but when Most became a main cast member in season two, Ralph was more commonly seen, and he, Richie, and Potsie (these two also later became roommates) became the three amigos. Known for saying "I still got it!" after delivering one of his jokes. Ralph left with Richie after the 1979–80 season to join the Army. Malph returned as a guest star in the final season, although he is absent in the finale (along with Potsie)—he is mentioned as having left to continue college to become an optometrist like his father.
• Chachi Arcola – Fonzie's younger cousin and later Al Delvecchio's stepson. Chachi is very close to his older cousin Fonzie. Fonzie acts as the older brother figure that Chachi needs. Chachi has a similar personality to his older cousin. He has Fonzie's smoothness and charisma, but Chachi is more laidback. Chachi becomes "one of the guys" as he gets older, joining Richie, Potsie, Ralph, and Fonzie in their antics. After Richie and Ralph leave the show, Chachi and Fonzie often have plots together. Chachi has a crush on Joanie Cunningham from the moment he meets her in season 5, but she initially thinks of him as a little kid, calling him names like "shrimp", "drip", etc. But as they enter high school, she too begins to find him attractive. In season 11, they broke up for a short period. But as the season progresses, they get back together and Chachi eventually proposes to Joanie and she says yes. The series finale features Chachi and Joanie's wedding.
• Al Delvecchio – From seasons four to nine (1976–82), Al became the new owner/cook of the drive-in after Arnold got married the previous season. Al later married Chachi's mother Louisa, thereby becoming Chachi's stepfather and Fonzie's uncle. Molinaro left Happy Days in 1982 to take his "Al" character to Joanie Loves Chachi, and returned as Al in three later episodes of Happy Days. Known for sighing "Yeeep, yep, yep, yep, yep" when he was disappointed or when things did not go his way.
• Mitsumo "Arnold" Takahashi (Noriyuki "Pat" Morita) (seasons 3, 10–11: 26 episodes) depicted the owner of Arnold's Drive-In for season three (1975–76). He stated that he obtained the moniker when he purchased Arnold's restaurant and people thought it was named after him, explaining that it was too costly to buy enough letter signs needed to rename it "Takahashi". He moonlighted as a martial arts instructor, teaching self-defense classes at the drive-in after hours. Morita also played "Arnold" as a guest star in 1977 and 1979 before returning as a recurring character after Al Molinaro departed in 1982.
• Jenny Piccalo – Joanie's boy-crazy best friend (1980–83), frequently mentioned but never seen in early episodes. She made her first on-screen appearance in the eighth season and remained a recurring character through the ninth season, becoming a regular during the tenth season in 1983. She returned as a guest star in the 1984 series finale. Jenny's father, played by Cathy Silvers' real-life father Phil Silvers, appeared in one episode.
• Roger Phillips (Ted McGinley) – Marion's nephew; coach and teacher at Jefferson High, until "Vocational Education" where he became principal at Patton High.[19] Introduced in 1980 after Richie left the show as a recurring character.
• Lori Beth Allen-Cunningham (Lynda Goodfriend) – Richie's girlfriend and later his wife (1977–82). She married Richie by phone in season eight. Fonzie helped Lori Beth deliver her baby in "Little Baby Cunningham". She returned as a guest star in the final season, where she is revealed to be pregnant with her second baby.
• Ashley Pfister (Linda Purl) – Divorced mother who becomes Fonzie's steady girlfriend until they broke up offscreen sometime before "Where the Guys Are". Purl also played as Richie's part-time girlfriend Gloria in season 2.

• Marsha Simms (Beatrice Colen) (seasons 1–3, 5; 22 episodes) – A carhop in the first two seasons. Appeared in the background of a few episodes during the first and second seasons before disappearing from the show in the third season. However, she later returned for a flashback guest appearance in the episode "Our Gang".
• Bobby Melner (Harris Kal) (seasons 8–11; 19 episodes) – Friend of Chachi and Joanie seen in episodes after Richie and Ralph left the show. He is a student in Fonzie's auto shop class, as well as in Roger's health class. At one point, he was also on the Jefferson High basketball team, and performed in a band with Joanie and Chachi.
• K.C. Cunningham (Crystal Bernard) (season 10; 15 episodes) – Howard's niece. She moved in with Howard and Marion after Joanie left for Chicago. She left an all-girls boarding school in Texas because it closed down. Her parents are always traveling. She also became friends with Jenny and she went on her first date with Melvin.
• Leopold "Flip" Phillips (Billy Warlock) (seasons 9 & 10; 13 episodes) – Roger's rebellious younger brother. He usually wears a shirt cut off over his bellybutton.
• Tommy (Kevin Sullivan) (seasons 8–11; 13 episodes) – Another friend of Chachi and Joanie in episodes after Richie and Ralph left the show. Like Bobby, Tommy is a student in Fonzie's auto shop class, as well as in Roger's health class. At one point, he was also on the Jefferson High basketball team, and performed in a band with Joanie and Chachi.
• Heather Pfister (Heather O'Rourke) (season 10; 12 episodes) – Ashley Pfister's daughter. Initially did not get along with Fonzie, but gradually learned to accept him as a father figure.
• Charles "Chuck" Cunningham (Gavan O'Herlihy, Randolph Roberts) (seasons 1 & 2; 11 episodes) – The oldest son of Howard and Marion Cunningham and older brother of Richie and Joanie, Chuck is a college student and basketball player. He is rarely seen and disappears without explanation in season two, never to be seen nor referenced again after "Fish and Fins". The character's disappearance gave rise to the pejorative term "Chuck Cunningham Syndrome", used to describe TV characters that disappear from shows without explanation and are later retconned to have never existed.[20] Gavan O'Herlihy played Chuck, but then he asked to leave the series.[21] He was replaced by Randolph Roberts. In several late-season episodes, Howard and/or Marion make reference to being "very proud of our two children," with no on-screen reference to Chuck.
• Eugene Belvin (Denis Mandel) (seasons 8 & 9; 10 episodes) – Nerdy classmate of Joanie and Chachi, and twin brother of Melvin Belvin. Is in Fonzie's auto shop class, and has a crush on Jenny Piccolo. Despite being a general stooge to his classmates at Jefferson High, he frequently tags along with Joanie and Chachi's circle of friends.
• "Bag" Zombroski (Neil J. Schwartz) (seasons 1–4; 9 episodes) – A schoolmate and leader of a gang called "The Demons".
• Police Officer Kirk / Army Reserve Major Kirk (Ed Peck) (seasons 3–10; 9 episodes) – Fonzie's nemesis and antagonist, who's eager to demonstrate his inflated sense of authority, and on the watch for delinquents and "pinkos" (communists). Kirk took over as acting Sheriff following the untimely death of Sheriff Flanaghan.
• Wendy (Misty Rowe) (season 2; 8 episodes) – A carhop from Arnold's in season two. She was paired with Marsha Simms in five episodes.
• Melvin Belvin (Scott Bernstein) (seasons 9 & 10; 8 episodes) – Nerdy classmate of Joanie and Chachi, and twin brother of Eugene Belvin. Like his brother, Melvin frequently tags along with Joanie's and Chachi's circle of friends. He once went on a date with K.C. Cunningham.
• Leather Tuscadero (Suzi Quatro) (seasons 5 & 6; 7 episodes) – Musician; younger sister of Pinky Tuscadero, and a former juvenile delinquent; formed her own girl group called "Leather and the Suedes".
• Jennifer Jerome (Lorrie Mahaffey) (seasons 5 & 6; 6 episodes) – Potsie's steady girlfriend. Mahaffey was Anson Williams' then wife.
• Laverne De Fazio (Penny Marshall) and Shirley Feeney (Cindy Williams) (seasons 3, 6 & 7; 5 episodes) – Dating interest of Fonzie, Laverne, and her friend, Shirley, appeared prominently in three episodes during the season three ("A Date with Fonzie", "Football Frolics", and "Fonzie the Superstar"), which led to the two starring in the spin-off series Laverne & Shirley; they also make guest appearances in the season six's "Fonzie's Funeral (Part 2)" and season seven's "Shotgun Wedding" (Part 1) (the second part of "Shotgun Wedding" concluded on a crossover episode of Laverne and Shirley.)
• Louisa Arcola-Delvecchio (Ellen Travolta) (seasons 8–11; 5 episodes) – Mother of Chachi Arcola; aunt of Fonzie.She married Al Delvecchio and they moved to Chicago.
• Gloria (Linda Purl) (season 2; 5 episodes) – Richie's occasional girlfriend in season two.
• Dr. Mickey Malph (Alan Oppenheimer, Jack Dodson) (season 3 & 4, 7; 4 episodes) – Ralph's father, an optometrist and, like his son, a self-styled comedian. Briefly separated from his wife Minnie, but apparently resolved issues with her after a talk with Ralph. It was Dr. Malph who convinced Fonzie to wear glasses after he started having vision problems.
• Raymond "Spike" Fonzarelli (Danny Butch) (seasons 2–4; 4 episodes) – Fonzie's cousin (often referred to as his nephew, but Fonzie explains that he couldn't be his nephew as Fonzie was an only child) and his copycat. He went on a date with Joanie in "Not with My Sister, You Don't" and made only fleeting appearances before the introduction of Chachi. The kinship between Spike and Chachi was never explained.
• Carol "Pinky" Tuscadero (Roz Kelly) (season 4; 3 episodes) – Former girlfriend of Fonzie and a traveling demolition derby driver.
• Clarence (Gary Friedkin) (season 10; 3 episodes) – A cook at Arnold's who is referred to several times throughout the show, but never actually seen until the episode "A Woman Not Under the Influence". There, it is revealed that Clarence is a little person. Clarence seems to have a good relationship with Al, but also frequently upsets him while goofing off in the kitchen.
• Bill "Sticks" Downey (John-Anthony Bailey) (season 3; 2 episodes) – Friend of Fonzie, Richie, Potsie and Ralph and drummer for their band, hence his nickname "Sticks", though he claimed he got the nickname because he was skinny.
• Grandma Nussbaum (Frances Bay) (seasons 9, 10 & 11: 3 episodes) – Chachi Arcola and Fonzie's grandmother. Grandma Nussbaum was played by Lillian Bronson in the season 3 episode, "Fonzie Moves In".

• Hank Aaron, the Milwaukee Braves home run king, appeared in season seven, episode nineteen
• Frankie Avalon appeared as himself (in season 9), singing his signature song "Venus" to a swooning Jenny Piccolo at the Leopard Lodge's annual "Poo Bah Doodah" musical
• Dr. Joyce Brothers (season 5, episode 19) appears as herself, trying to help Fonzie's dog out of a depression
• Julie Brown made her television debut in the seventh-season episode "Ahhh Wilderness" as one of three girls who went camping with Richie, Fonzie et al.
• Morgan Fairchild appears in season five, episode ten as a snooty rich socialite who tries to humiliate Fonzie
• Herbie Faye appeared as 'Pop' in the 1974 episode "Knock Around the Block"
• Lorne Greene made a brief walk-on cameo during the season five premiere, which took place in Hollywood
• Tom Hanks appeared in an episode as a character seeking revenge on Fonzie for pushing him off a swing when the two of them were in the 3rd grade; the confrontation occurs just as Fonzie was about to be given a community leader award
• John Hart (TV's The Lone Ranger) appeared in season 9, episode 17 where Fonzie meets his childhood idol (Hart's last acting job)
• Christopher Knight (Peter Brady on The Brady Bunch) played Joanie's boyfriend on the season five episode "Be My Valentine"
• Cheryl Ladd appeared in "Wish Upon a Star" (season 2), playing the part of a Hollywood starlet Richie wins a date with
• Michael McKean and David L. Lander, of Laverne & Shirley, portrayed their "Lenny" and "Squiggy" characters in the sixth-season episode "Fonzie's Funeral (Part 2)"
• Eddie Mekka, also from Laverne & Shirley, portrayed his "Carmine" character in the season four's "Joanie's Weird Boyfriend" and the season six's "Fonzie's Funeral (Part 2)"
• Maureen McCormick (Marcia Brady on The Brady Bunch) was "Hildie" in season 2, episode 16
• James Millhollin, a character actor, made the last television appearance of his career as Mr. Rudi in the 1979 episode "Potsie Quits School"
• James Randi ("The Amazing Randi") appeared as himself in the episode "The Magic Show" (season 6)[22]
• Buffalo Bob Smith and Bob Brunner as Clarabell the Clown appeared in the episode "The Howdy Doody Show" (season 2); the characters come to town looking for Howdy Doody look-alikes
• Craig Stevens, the star of detective show Peter Gunn played Ashley Pfister's father in "Hello Pfisters" (season 10)
• Danny Thomas appeared in the episode "Grandpa's Visit" (season 5) as Sean Cunningham, Howard's father.
• Charlene Tilton appeared in the episode "They Shoot Fonzies, Don't They?" (season 4) as Jill Higgins, who challenges Fonzie and Joanie at a dance marathon until Fonzie might have to get a crewcut.
• Robin Williams appeared in two episodes as Mork from Ork; in season five's "My Favorite Orkan", Mork wants to take Richie back to Ork with him to study earthlings, which led to the spin-off Mork & Mindy; season six's "Mork Returns" aired during the height of the popularity of Mork and Mindy
• Lyle Waggoner appeared in the episode "Dreams Can Come True" (season 8) as Bobby Burns, host of the titular game show on which Marion appears as a contestant, and again in the episode "Like Mother, Like Daughter" (season 11) as Frederick Hamilton, Marion's former college boyfriend.

• Jerry Paris, who played next-door neighbor Jerry Helper on The Dick Van Dyke Show and directed 84 episodes of that series,[27] directed every episode of Happy Days from season three on, except for three episodes in season three ("Jailhouse Rock", "Dance Contest" and "Arnold's Wedding").[28]
• Producer and writer Bob Brunner created Arthur Fonzarelli's "Fonzie" nickname and his iconic comeback phrase, "Sit on it."[16][17][18]
• Beginning in September 1979 until the show went out of production, reruns of the show were syndicated under the title Happy Days Again.
• Happy Days was produced by Miller-Milkis Productions, a teaming of Thomas L. Miller with former film editor Edward K. Milkis, which became Miller-Milkis-Boyett Productions when Robert L. Boyett joined the company in 1980, and was the first-ever show to be produced by the company's most recent incarnation, Miller-Boyett Productions, which followed Milkis's resignation from the partnership. It was also produced by Henderson Productions and was one of the popular shows produced in association with Paramount Television.
• In its 11 seasons on the air, Happy Days is the second-longest-running sitcom in ABC's history (behind The Adventures of Ozzie and Harriet, which ran 14 seasons, from 1952 to 1966), and one of the longest-running primetime programs in the network's history. It is also unique in that it remained in the same time slot, leading off ABC's Tuesday night programming at 8:00 p.m. Eastern/Pacific (7:00 p.m. in the Central and Mountain zones) for its first ten seasons. That half-hour became a signature timeslot for ABC, with Who's the Boss? instantly entering the top 10 when it was moved from Thursdays and staying in that time slot for six seasons, followed by the equally family-friendly sitcom Full House (another Miller-Boyett co-production). That sitcom also hit the top 10 immediately after inheriting the Tuesday at 8:00/7:00 p.m. slot and then stayed there for four seasons.
• Happy Days also proved to be quite popular in daytime reruns; they joined the ABC daytime schedule in 1975, airing reruns at 11:30 a.m. ET (10:30 a.m. CT/MT/PT), being moved to 11:00/10:00 a.m. in 1977, paired with Family Feud following at 11:30/10:30 a.m. It was replaced on the daytime schedule by reruns of its spin-off, Laverne & Shirley, in April 1979.
• CBS programming head Fred Silverman scheduled the Maude spin-off Good Times directly against Happy Days during their respective second seasons in an attempt to kill the ABC show's growing popularity. In a way this move backfired on Silverman, as he was named president of ABC in 1975, thus forcing him to come up with a way to save the show he tried to kill the year before. After having knocked Happy Days out of the top 20 programs on television his last year at CBS, Silverman had the series at the top of the Nielsen ratings by 1977 (see below). Good Times was later cancelled in 1979.
• Ron Howard later revealed that many of the exterior scenes filmed in Happy Days were actually shot in Munster, Indiana.
• The official series finale ("Passages") aired on May 8, 1984. But there were five "leftover" episodes that ABC didn't have time to air during the regular season due to the Winter Olympics and the spring run of a.k.a. Pablo. Four of these aired on Thursday nights during the summer of 1984; the fifth ("Fonzie's Spots") aired on September 24, 1984.

The first two seasons of Happy Days (1974–75) were filmed using a single-camera setup and laugh track. One episode of season two ("Fonzie Gets Married") was filmed in front of a studio audience with three cameras as a test run. From the third season on (1975–84), the show was a three-camera production in front of a live audience (with a cast member, usually Tom Bosley, announcing in voice-over, "Happy Days is filmed before a live audience" at the start of most episodes), giving these later seasons a markedly different style. A laugh track was still used during post-production to smooth over live reactions.

Garry Marshall's earlier television series The Odd Couple had undergone an identical change in production style after its first season in 1970–71.

Richie and Fonzie view his destroyed motorcycle in his living room, 1976. Fonzie's apartment was over the Cunninghams' garage.

The show had two main sets: the Cunningham home and Arnold's/Al's Drive-In.

In seasons one and two, the Cunningham house was arranged with the front door on the left and the kitchen on the right of screen, in a triangular arrangement. From season three on, the house was rearranged to accommodate multiple cameras and a studio audience.

The Cunninghams' official address is 565 North Clinton Drive, Milwaukee, Wisconsin.[29] The house that served as the exterior of the Cunningham residence is actually located at 565 North Cahuenga Boulevard (south of Melrose Avenue) in Los Angeles,[30] several blocks from the Paramount lot on Melrose Avenue.

The Milky Way Drive-In, located on Port Washington Road in the North Shore suburb of Glendale, Wisconsin (now Kopp's Frozen Custard Stand), was the inspiration for the original Arnold's Drive-In; it has since been demolished. The exterior of Arnold's was a standing set on the Paramount Studios lot that has since been demolished. This exterior was close to Stage 19, where the rest of the show's sets were located.

The set of the diner in the first season was a room with the same vague details of the later set, such as the paneling, and the college pennants. When the show changed to a studio production in 1975, the set was widened and the entrance was hidden, but allowed an upstage, central entrance for cast members. The barely-seen kitchen was also upstaged and seen only through a pass-through window. The diner had orange booths, downstage center for closeup conversation, as well as camera left. There were two restroom doors camera right, labeled "Guys" and "Dolls". A 1953 Seeburg Model G jukebox (with replaced metal pilasters from Wico Corp.) was positioned camera right, and an anachronistic "Nip-It" pinball machine (actually produced in 1972) was positioned far camera right.

Potsie, Richie, Fonzie, and Ralph Malph at Arnold's

College pennants adorned the walls, including Purdue and University of Wisconsin–Milwaukee, along with a blue and white sign reading "Jefferson High School". Milwaukee's Washington High School provided the inspiration for the exteriors of the fictional Jefferson.

In a two-part episode from the seventh season, the original Arnold's Drive-In was written out of the series as being destroyed by fire (see List of Happy Days episodes, episodes 159 and 160). In the last seasons that covered the 1960s timeline, a new Arnold's Drive-In set (to portray the new Arnold's that replaced the original Arnold's destroyed by the fire) emerged in a 1960s decor with wood paneling and stained glass.

In 2004, two decades after the first set was destroyed, the Happy Days 30th Anniversary Reunion requested that the reunion take place in Arnold's. The set was rebuilt by production designer James Yarnell based on the original floor plan. The reunion special was taped at CBS Television City's Bob Barker Studio in September 2004.[31]

Season one used a newly recorded version of "Rock Around the Clock" by Bill Haley & His Comets (recorded in the fall of 1973) as the opening theme song. This recording was not commercially released at the time, although the original 1954 recording returned to the American Billboard charts in 1974 as a result of the song's use on the show. The "Happy Days" recording had its first commercial release in 2005 by the German label Hydra Records. (When Happy Days entered syndication in 1979, the series was retitled Happy Days Again and used an edited version of the 1954 recording instead of the 1973 version.) In some prints intended for reruns and overseas broadcasts, as well as on the Season 2 DVD set release and later re-releases of the Season 1 DVD set, the original "Rock Around the Clock" opening theme is replaced by the more standard "Happy Days" theme, because of music rights issues.

The show's closing theme song in seasons one and two was a fragment from "Happy Days" (although in a different recording with a different lyric from that which would become the standard version), whose music was composed by Charles Fox and whose lyric was written by Norman Gimbel. According to SAG, this version was performed by Jim Haas on lead vocals, The Ron Hicklin Singers, Stan Farber, Jerry Whitman, and Gary Garrett on backing vocals, and studio musicians.

From seasons three to ten inclusive, a longer version of "Happy Days" replaced "Rock Around the Clock" at the beginning of the show. Released as a single in 1976 by Pratt & McClain, "Happy Days" cracked the Top 5. The show itself finished the 1976–77 television season at #1, ending the five-year Nielsen reign of All in the Family.

For the show's 11th and final season (1983–84), the theme was rerecorded in a more modern style. It featured Bobby Arvon on lead vocals, with several back-up vocalists. To accompany this new version, new opening credits were filmed, and the flashing Happy Days logo was reanimated to create an overall "new" feel which incorporated 1980s sensibilities with 1950s nostalgia (although by this time the show was set in 1965).

On April 19, 2011, Happy Days co-stars Erin Moran, Don Most, Marion Ross and Anson Williams, as well as the estate of Tom Bosley (who died in 2010), filed a $10 million breach-of-contract lawsuit against CBS, which owns the show, claiming they had not been paid for merchandising revenues owed under their contracts.[32] The cast members claimed they had not received revenues from show-related items, including comic books, T-shirts, scrapbooks, trading cards, games, lunch boxes, dolls, toy cars, magnets, greeting cards and DVDs where their images appear on the box covers. Under their contracts, they were supposed to be paid 5% of the net proceeds of merchandising if their sole image were used, and half that amount if they were in a group. CBS said it owed the actors $8,500 and $9,000 each, most of it from slot machine revenues, but the group said they were owed millions.[33] The lawsuit was initiated after Ross was informed by a friend playing slots at a casino of a Happy Days machine on which players win the jackpot when five Marion Rosses are rolled.

In October 2011, a judge rejected the group's fraud claim, which meant they could not receive millions of dollars in potential damages.[34] On June 5, 2012, a judge denied a motion filed by CBS to have the case thrown out, which meant it would go to trial on July 17 if the matter was not settled by then.[35] In July 2012, the actors settled their lawsuit with CBS. Each received a payment of $65,000 and a promise by CBS to continue honoring the terms of their contracts.[36][37]

A series of novels based on characters and dialog of the series was written by William Johnston and published by Tempo Books in the 1970s. A (possibly unofficial) reimagining titled Who Killed the Fonz? continues the story in the 1980s as a murder mystery. It was published in hardcover on February 19, 2019, and written by James Boice.[44]

Western Publishing published a Happy Days comic book series in 1979 under their Gold Key Comics brand and Whitman Comics brand.

There are two animated series, both produced by Hanna-Barbera Productions in association with Paramount Television (now known as CBS Television Distribution). The Fonz and the Happy Days Gang ran from 1980 to 1982. There are also animated spin-offs of Laverne & Shirley (Laverne & Shirley in the Army) and Mork & Mindy (centering on a young Mork and Mindy in high school). The following season, they were connected together as Mork & Mindy/Laverne & Shirley/Fonz Hour (1982).[45]

In the late 1990s, a touring arena show called Happy Days: The Arena Spectacular toured Australia's major cities.[46] The story featured a property developer, and former girlfriend of Fonzie's, called Miss Frost (Rebecca Gibney), wanting to buy the diner and redevelop it. It starred Craig McLachlan as Fonzie, Max Gillies and Wendy Hughes as Mr. and Mrs. Cunningham, Doug Parkinson as Al, and Jo Beth Taylor as Richie's love interest Laura. Tom Bosley presented an introduction before each performance live on stage, and pop group Human Nature played a 1950s-style rock group.

Another stage show, Happy Days: A New Musical, began touring in 2008.[47][48]

Happy Days appeared on a music video for the song "Buddy Holly" by Weezer. Where they talked about Mary Tyler Moore who is an actress known for The Dick Van Dyke Show and who appeared as "Happy Hotpoint", a tiny elf dancing on Hotpoint appliances in TV commercials during the 1950s series Ozzie & Harriet, going with the line "Ooo Wee Ooo I look just like Buddy Holly, Oh Oh and you're Mary Tyler Moore".