|Genre||Animated Series, Comedy|
|Created by||Peter Hannan|
|Voices of||Tom Kenny
|Country of origin||United States|
|No. of seasons||3|
|No. of episodes||66 (List of episodes)|
|Running time||22 minutes|
|Original run||October 4, 1998– July 24, 2004|
CatDog is an American animated television series which was first aired on October 4, 1998 with the last show airing on July 24, 2004. The series was created for Nickelodeon by Peter Hannan. It was also shown as a sneak peek in theaters with The Rugrats Movie. The series depicts the life of conjoined brothers, with one half being a Cat while the other a dog. Nickelodeon at first ordered 40 episodes and planned to debut it in fall 1998. Nick produced the series from Burbank, California, United States.
The show had average ratings, but it managed to maintain a moderate yet loyal fan base. Towards the end of the series run, a made-for-TV movie was released, titled CatDog: The Great Parent Mystery.
The show follows the adventures of CatDog, a hybrid of a cat and dog. Because of their strange condition, CatDog are seen as outcasts in the city of Nearburg and are often harassed by the Greaser Dogs, a gang of rough thugs, and their neighbor, Winslow, a devious blue mouse.
Albie Hecht, Nickelodeon's senior vice president of worldwide productions, said that the creators planned for the show to "really play off of kids' sympathies" by portraying the characters as experiencing "the worst of both worlds". 
The show revolves around Cat and Dog, who share the same body, and although they are best friends and brothers, they have very different personalities, similar to The Odd Couple mixed with elements of Laurel and Hardy and Abbott and Costello. Cat is very cultured while Dog is very fun-loving and enjoys chasing garbage trucks, chasing cars, and exploring many things to which Cat does not want to take part in.
Cat (voiced by Jim Cummings) is the smarter, cleverer and more cunning of the two. He often devises plans to trick Dog into getting what he wants, such as making Dog smarter in an attempt to have more in common with him, or having him win a dog sledding contest by training him in a very hard and militaristic manner, and usually, as a result of his greediness and selfishness, these schemes all blow up in his face. He is the "underdog" of the two. Life has been hard for the both of them, as they have been shunned by society due to their awkward appearance, but Cat always seems to get the short end of the stick in the situations, especially faced with the Greaser Dogs. With his brains and constant ridiculing from the rest of the characters, he's the most defensive and short tempered of the two. Despite his quirks and spats with Dog, he loves his brother with his whole heart. He cares so deeply that he ends up helping Dog in the end once his guilty conscience gets to him.
Cat desires fame and fortune, and tends to go to excessive lengths in order to gain them. He is intelligent and enjoys reading, gardening, and listening to classical music. Cat is somewhat uptight and believes strongly in being polite and neat. He is a stickler for cleanliness and, like most cats, is aquaphobic. He is also obsessed with jet skis, once stating that he would sell his soul for one.
Dog (voiced by Tom Kenny) is the more happy-go-lucky and more naïve of the two. He is also the source of clumsiness. He is extremely ambitious when Cat or any other character convinces him to take on a task, diving right into it with full force and energy. Dog is the typical loyal "dumb dog" and is easily convinced. He will believe everything he is told. His attention span is very short and he is easily distracted by garbage trucks, bones, food, and his overactive imagination. Because of his dysfunctional brain, Dog usually is the one who gets the pair into trouble. Not paying attention to Cat's warnings, his actions almost always end up with some severe consequences. Despite this, in many of the episodes, it is shown that Dog is usually the one that is more popular and athletic of the two, such as the episode when Cat and Dog both went back to school to complete Cat's last day of High School. Like Cat, Dog adores his brother and looks up to him no matter how many times Cat steers him into danger.
Dog is the typical animal. He is often distracted with chasing shadows, and loves eating garbage, chasing after tennis balls, and eating. Much to Cat's dismay, he leaves a mess everywhere he goes. According to the series finale, Dog remembers what their parents were like (ex.: "Mom's four eyes; Dad's slimy green skin.")
Winslow T. Oddfellow (voiced by Carlos Alazraqui) lives in CatDog's house in the hole in the wall. Despite his rat-like appearance and behavior, he is actually a mouse. Winslow speaks with a typical Brooklyn accent. Winslow is always full of wisecracks about anything and everything. He's very sneaky and underhanded with CatDog, especially with Cat. Winslow and Cat do not get along at all, because he's always getting Cat in trouble. Dog, however, doesn't mind Winslow and is friendly with him. Deep down, he has a very big heart and loves CatDog and at some point act as CatDog's conscience and guidance of living in society, but acts out against them because he is jealous of how close they are. When he laughs, he goes "Heh Heh".
Rancid Rabbit (voiced by Billy West) is the stereotypical authority figure and one of the show's main antagonists. He has had job titles like police officer, life guard, prison guard , boss of various businesses, principal, president, mayor, Egyptian Pharaoh, doctor, TV host, contest judge, store and Taco Depot manager, etc. Rancid hates CatDog and will go out of his way to punish them or force them to work for him, abusing his power to the fullest degree. Rancid takes advantage of CatDog as much as he can by deceiving them into buying his products or pushing them to do his bidding in a job. He does whatever it takes to take their money or benefit himself in any way. He constantly says "Leaping Lumbago" and "What, What, What". Rancid serves as one of the primary antagonists in the show. Apparently, Rancid owns a mall called the Mall of Malls (a parody of the Mall Of America), and has a spoiled niece named Rancy.
The Greaser Dogs are a street gang consisting of three tough dogs named Cliff, Shriek and Lube as well as the show's main antagonists. They perform as the primary antagonists in the show, next to Rancid Rabbit. They act no different than school playground bullies, picking on anyone either weaker or different than them. They pick on CatDog (mostly Cat), and their only reason seems to be "CatDog's a FREAK!" Their usual nickname for them is "Catbutt," because Dog has Cat for a butt. Dog sometimes gets along with them because he's a canine, as well. They initiated him in the gang in the episode "Full Moon Fever", after he had proven his worth as a "real" dog.
Eddie, a squirrel, is a Greaser wannabe with little red pieces of paper taped to the side of his head to look like red sideburns in hopes to be more like Cliff. He is always bruised up from getting punched, and from being used as a birdie in badminton, or a football. He wants to be an official Greaser very badly, but sadly lacks their number one requirement: being a dog.
Randolph is a trendy, suave cat who has an accent like Cary Grant. He first appears in the episode "CatDog's End". He'll try anything once, as long as it's terribly exciting and attention-getting. Randolph appears to be like a celebrity in his lifestyle. In "All About Cat", Randolph was hosting the musical awards banquet. "In the Lady is a Shriek", Randolph is the proud owner of "Randolph's Charm School and House of Beauty", to help turn girls into beautiful women with poise and etiquette. That's Randolph; a trend setting, rich and famous cat. He constantly says "I love it."
Tallulah is an actress on whom Cat has an enormous crush. CatDog first met Tallulah during the musical "Abe Lincoln Superstar". Since then, she has become a major celebrity and good friend of Randolph's. Tallulah is forever searching for her soul mate that's "as loyal as a dog and as clever as a cat, who will take [her] in his arms and say 'Baby, you're the one!'"
The fictional super hero is Dog's ultimate hero. Having watched Mean Bob movies, playing the video games and with the toys, Dog is quite an expert on Mean Bob and how to do certain things like dodge meteors, fly and shoot at enemy ships, and battle "Salivians". Mean Bob has made appearances as an action figure, or actor, in The Collector, Spaced Out, Dog Show, the Golden Hydrant Game, and Saving Mean Bob game.
Mervis (a pig) and Dunlap (a weasel) are CatDog's best friends and are often used as background characters. Dunlap appears to be the luckier of the two due to his fortunes, like getting a promotion at a job, in contrast to Mervis' misfortunes, such as getting into an accident because of the Greasers. A running gag through out the series is that Mervis and Dunlap can sometimes be seen fighting.
Mr. Sunshine is a green shirtless creature with a tail and no apparent emotions. Very little is known about him or his species.