CatDog is an American animated television series created for Nickelodeon by Peter Hannan. The series depicts the life of conjoined brothers, with one half being a cat and the other a dog. Nickelodeon produced the series from Burbank, California. The first episode aired on April 4, 1998, before the show officially premiered in October. The episode "Fetch" was also shown in theaters with The Rugrats Movie.

Toward the end of the series run, a made-for-TV film was released, titled CatDog: The Great Parent Mystery. Reruns were played on Nicktoons until 2011 and later aired on TeenNick as part of The '90s Are All That block. The series is produced by Nickelodeon Animation Studio and Peter Hannan Productions and has been released on DVD.