Generator Rex

• Rex Salazar: The title character of the show. He is a willful, carefree, sensitive, easygoing person of Hispanic origin; half Argentinean and half Mexican. He speaks English and Spanish. He is the second child and youngest son of Rafael and Violetta, who had died five years prior to the series in the Nanite Explosion. At the young age of ten, he was fatally hurt in an unspecified industrial accident. To save his life, his parents and older brother, Caesar, had infused him with the original batch of fully programmed, highly evolved nanites, which granted him several unique technopathic and mechanical abilities as side effects. Suffers from repeat memory loss which has him count on Providence to help him discover who he used to be. In one of his "past lives", Rex became the leader for a crime gang in Hong Kong, Skwydd, Tuck, and Cricket were his gang while he was the top man for Quarry, a Golem type EVO crime boss. His main love interest and girlfriend is Circe, though he is considered a ladies-man.
• Six: The sixth most dangerous man on the planet. He has romantic feelings for Rebecca Holiday. Previously grouped with four other mercenaries under the leadership of his mentor, number One, whom became corrupted into an EVO with the nanite explosion and fought off the infection for 5 years becoming "one with" the world. Rex is the cause for him to change his life around to start caring for others, finding Rex with a blank memory after a mega robot EVO destroys a town, and discovers that he can cure EVOs.
• Dr. Rebecca Holiday: The lead scientist at Providence and Rex's caretaker. She has a younger sister, Beverly, who turned into an incurable E.V.O. at thirteen. She has romantic feelings for Six.
• Bobo Haha: An E.V.O. monkey with the ability of human speech. He is Rex's sidekick and fellow prankster. Self proclaimed bad influence on Rex.
• White Knight: The hardhearted leader of Providence. Self proclaimed to be the only man who can be trusted to run Providence due to an accident involving Six, his partner at the time, and Rex, the newly discovered EVO at the time causing him to be nanite free, preventing him from EVO corruption.
• Noah Nixon: A non E.V.O. who has cropped blonde hair and pale blue-green eyes. He is Rex's first best friend who was initially working for White Knight to "keep an eye on Rex." He has a thing for Claire. Declared by Bobo Haha to be the King of Pranks, a champion table tennis player, and shoots a good hoop in basketball.
• Caesar Salazar: The eccentric, slightly mad scientist and older brother of Rex. He was first referenced in "Dark Passage" by Dr. Gabriel Rylander. He arrives in a mobile lab back on the planet with time displacement five years after the nanite explosion and immediately goes to protect the Omega Nanite, and his little brother. Sometimes his priorities are vague to his little brother.

• Van Kleiss: The main villain of the series, and Rex's archenemy. Heavily tied to Rex's past he offers the promise of helping him gain some old memories if he joins him. Programmer for interface technology with the nanites, and can create EVOs. Last seen being taken by Breach presumably to her alternate dimension.
• Biowulf: A biomechanical wolf-like E.V.O. who is the second-in-command of Van Kleiss' followers, the Pack.
• Breach: A young E.V.O. girl with four arms, pale white skin, and the ability to create red portals to any destination. Obsessed with Rex for his unique qualities, she once kidnapped him to put in a pocket dimension, where she has everything just as she likes it. Van Kleiss forces her into time travel technology, and an insurance protocol sends her scattered through time, and Rex helps her from his grasp, helping her to become her own person. It is unclear if he and Breach are friends, but they both hope for it.
• Skalamandar: A green lizard E.V.O. who is constantly drooling due to his head being on sideways that can project dozens of crystals from his arms, and form crystal walls.
• Circe: Rex's main love interest/girlfriend in the show. She is a human-looking E.V.O. with unusually strong powers over sound and certain types of songs which she uses to allure and summon fellow E.V.O.s to her. She finally admitted her true and mutual romantic feelings for Rex, in the form of a passionate kiss, and let him escape. In "Mind Games", a former partner-in-crime of Rex's used his shape-shifting ability to take on her form to mess with Rex's confidence. At Providence, Circe is shown to be imprisoned in a cell with her mouth gagged by a muzzle to prevent her from using any of her E.V.O. abilities to retaliate. The commotion outside her cell caught her attention and she had stepped forward to see what was going on. Most unfortunately, the show ended before she and Rex's romance could be explored further.
• NoFace: is a supremely powerful and vengeful faceless E.V.O. with the ability to communicate with intelligent E.V.O.s and control the less intelligent ones. During the nanite event, the Gulf Stream funneled a huge amount of active nanites into the city of Kiev, Ukraine, transforming nearly all that lived there into extremely powerful E.V.O.s. Among them was their current leader, NoFace. In response to the chaos, all humans were evacuated and the city quarantined via a massive one-way spherical force field.
• Black Knight: The main villain of Season Three. She has blue-black hair in a bob cut and is the new leader of New Providence, replacing White Knight six months in the future. She is very power-hungry and crafty in order to achieve her sinister goals for absolute power. She is linked to Rex's past as well, presumably being part of the cause for the Nanite Explosion. Under her rule, remote controlling collars are placed on EVOs that are captured, and unruly operatives such as Bobo Haha, which at the flip of a switch can force them to be docile, or attack, and the EVOs are completely aware of their actions while they can do nothing about it. Seized game control units for the collars from Quarry's Arcade, and formed a massive Black Knight robot with four others to fight Rex in the pursuit of becoming a god.

• Claire Bowman: A teenage student in high school with Noah, who has a crush on her. Highly intelligent in science.
• Annie: A good friend of Claire's who possesses supernatural clumsiness, earning her the nickname of "Blonde Widow". Almost killed Rex on prom night.
• Tuck: An old companion of Rex and his old street gang who reside in Hong Kong, China. He is a mummy-like E.V.O. who can elongate his limbs. When Rex chases Breach to Hong Kong, he recognizes a blossoming romance between Tuck and Cricket before they realize it, and while they say they are only friends, as Rex leaves, Tuck and Skwydd chase down Circe and Cricket attempting a double date.
• Skwydd: A squid-like E.V.O. with pale green skin and tentacles. He can emit smoke-like ink from his mouth for cover. When his nanites are supercharged his ink can consolidate and grab things. Rex recognizes an admiration between him and Circe after chasing Breach to Hong Kong and says he's alright with it. Skwydd says they are only friends but once Rex leaves, He and Tuck chase down Cricket and Circe attempting to ask them on a double date.
• Cricket: A cricket-like E.V.O. who has had a crush on Rex for a long time. She is good "girlfriends" with Circe, and Rex assumed that she and Tuck were becoming a couple, which she declares they are strictly platonic.
• Beverly Holiday: The younger sister of Dr. Holiday who became a mindless spider-like E.V.O. at thirteen. Although incurable, she was finally cured in "A Family Holiday" and reunited with her elder sister. She likes the band Trendbenders.

Warner Home Video released Volume 1 DVD, a two-disc set that contains the first nine episodes of the series on October 19, 2010.[6]

A video game, entitled Generator Rex: Agent of Providence, has been developed for Wii, PlayStation 3, Nintendo DS, Nintendo 3DS and Xbox 360. The game was released on November 1, 2011 in the United States, published by Activision.[7][8] The plot involves Van Kleiss attempting to find blueprints to build an Omega-One Nanite. All voice actors reprise their roles from the series. Agent of Providence was given an E10+ rating by ESRB.[9] The game was also scored by the series' composer, Kevin Manthei.[10]

Mattel has produced a toy line based on the series. For the main figures each is approximately 4 inches tall and packaged with an ordinary day E.V.O. There were also deluxe figures, EVO attack packs, as well as other waves and lines that were never released including a line from MEGA Bloks was announced (in 2010) featuring construction sets.[11]

Cartoon Network has featured Generator Rex and Ben 10 in their and DC Comics's Cartoon Network: Action Pack comic books.[12] Two 3D picture books (featuring cardboard 3D glasses) "EVOs and Heroes," a whole analysis on characters and their abilities and "The Swarm," an adaption of the episode of the same name, where Rex must fight insect E.V.O.s that feed on metal, have also been released.[12] For beginning readers, the story "Leader of the Pack" is also based on an episode and features Rex and Bobo being captured and locked in an underground prison cell.[12]

In February 2013, IDW Publishing announced a partnership with Cartoon Network to produce comic books and issues based on its properties. Generator Rex along with Ben 10 was one of the titles announced to be published.[13]