Rex the Runt

• Rex, the protagonist — a timid, irritable runt. He is quick-witted and usually comes up with plans to get out of the scrapes the gang finds themselves in. However, he can also annoy the others by being a smart aleck. His favourite superhero is Rocket Raymond.
• Bad Bob is a "big, fat slob", interested in food and TV. His friends, and occasionally even he himself, describe him as a "Big, fat, jelly-wobbly, fat bast-", usually getting cut off towards the end. He is distinguishable by his eye patch, which changes from eye to eye, and often carries around a revolver almost the size of himself. However grumpy he might be, he is intelligent and loyal.
• Wendy is the only female housemate, distinguishable by her eyelashes, pink colour, noticeably hemispheric breasts, and wears a pink bow on her head. She is cynical, sarcastic, and fiercely independent. Wendy provides solutions to problems albeit in a distant or non-caring way. She speaks in a Mancunian accent.
• Vince is the pet of the household, although all four are dogs. He is distinguished by his prominent buckteeth and mismatched eyes. He speaks in single words or short disjointed phrases, his favourites being "Spaghetti", "Tuesday", "Jam", and "Trousers". Vince suffers from "Random Pavarotti Disease", causing him to randomly blurt out snatches of opera. While he appears to be unintelligent, he occasionally shows great ingenuity, for example by building an elaborate Heath Robinson machine designed to kill a mouse. The other members of the gang often respond to Vince's random outbursts by irritably telling him to "shut it". Vince often has a habit of copying what others have said, sometimes even if they have just said it in their minds, which Bad Bob finds really annoying.

Many one-off and recurring characters in Rex The Runt are voiced by various well-known UK celebrities. These include:

• Doctor Dogg is a medical doctor. Moustachioed, complacent and greedy, he's an opportunistic money-grabber, whose habitual charge for any treatment is "ten quid" - regardless of whether the cure works or does more harm than good. He isn't above using the main characters in medical research. Voiced by Paul Merton.
• Arthur Dustcart, another semi-regular character, who first makes an appearance in the last episode of the first series, but appears quite frequently in the second. He is an ugly but experienced dustman, sporting sleepy mismatched eyes, a neckerchief, a pair of dirty underpants and a large nose with prominent nasal hair. Despite his grotesque appearance and smell, he and Wendy get on rather well, much to the annoyance of Rex. He becomes a friend of the household when he helps find Rex after he was turned into spaghetti.
• Mrs. Bloomers, head of Kumfy Kennels. Treats dogs with care, until she put Vince in the kennel and he ate a chihuahua.
• Judith Poodle, hostess of a holiday program. Usually ends her sentences with "Ruff!"
• Mr. Formal, the Runts' bank manager, until Bad Bob brought his gun and made him think they were bank robbers.
• Melting Blob Slime, a three-year-old, but very smart slime creature who warned the Runts about the black hole.
• Kylie Mandlebrotska, Rex's old math teacher, until she fell into the black hole.
• Easter Island Aliens, three space aliens from the planet Thribb, where the people look like the Moai statues from Easter Island.
• Mr Chittock, angry neighbour to Rex, after the gang went into his house and drank his beer. Voiced by veteran alternative comedian Stephen Frost.
• Johnny Saveloy, a teenage sausage who was really very old but was kept in a state of artificial youth due to the Church of Chemicology. Voiced by Bob Monkhouse.
• Stinky Basil, a smarmy French talent-spotter. Voiced by Antoine De Caunes, known best in the UK for presenting the Channel 4 late-night adult entertainment show Eurotrash.
• The Happy Rabbits, a band who may sing beautifully but are really cranky and will not let anybody stand in their way.

• Andrew Franks as Rex (series 1)
• Colin Rote as Rex (series 2)
• Kevin Wrench as Bad Bob (series 1)
• Andy Jeffers as Bad Bob (series 2)
• Elisabeth Hadley as Wendy
• Steve Box as Vince
• Paul Merton as Doctor Dogg
• Arthur Smith as Arthur Dustcart

These include:

• Morwenna Banks as Mrs Bloomers ("A Holiday in Vince")
• Judith Chalmers as Judith Poodle ("A Holiday in Vince", "The Trials of Wendy")
• Bob Holness as Mr Formal ("Adventures on Telly, Part I")
• Eddie Izzard as Melting Blob Man ("Adventures on Telly, Part III"), and Easter Island Head Aliens ("Easter Island")
• Kathy Burke as Kylie Mandelbrotska ("Adventures on Telly, Part III", "Rocket Raymond", "Wendy's New Hair Do")
• Antoine de Caunes as Stinky Basil ("Too Many Dogs", "Stinky's Search for a Star", "Bob's International Hiccup Centre"), and French Delegate ("Bob's International Hiccup Centre")
• June Whitfield as Judge Pikelet ("The Trials of Wendy")
• Simon Day as Constable Funnyname ("The Trials of Wendy", "Stinky's Search for a Star", "Bob Joins a Gang")
• Pam Ayres as Aunty Brenda ("Under the Duvet", "Slim Bob")
• Stanley Unwin as Mr Wangle, Accountant to the Stars ("Johnny Saveloy's Undoing")
• Bob Monkhouse as Johnny Saveloy ("Johnny Saveloy's Undoing", "The City Shrinkers")
• Tommy Cannon as Tiddles the Destroyer ("Mouse in Me Kitchen")
• Graham Norton as Osvaldo Halitosis ("Patio") and the Plants ("A Crap Day Out")
• Bobby Ball as Wayne ("Wayne the Zebra")
• Phill Jupitus as Morris the One-Gloved Mouse ("Mouse in Me Kitchen"), The Ants ("Patio") and Sergeant Major ("Private Wendy")
• Jonathan Ross as Handsome Rex ("Wendy's Hot Date") and Awards Announcer ("Wendy's New Hairdo")
• Loyd Grossman as himself ("The Art of Cooking")

Series One has been released on VHS in the United Kingdom by Universal Pictures UK on September 24, 2001. The series was also released on DVD in South Korea.

A DVD of all 26 episodes has been released in the United States by A&E Home Video, which is region-free.

A few episodes of the series were also included on the DVD Aardman's Darkside, released in October 2006.

A book written by Andrew Franks and Kevin Wrench (the voices of Rex and Bad Bob) titled Rex The Runt: Rainy Day Companion was released.

Plush toys of the four main characters were available via Aardman at one point, as well as a handbag of Vince's head, though this is particularly rare.

Sweets shaped like the main characters were available in the early 2000s