The Ren & Stimpy Show, commonly referred to as simply Ren & Stimpy, is an American animated comedy television series created by John Kricfalusi and developed by Kricfalusi, Bob Camp, Jim Smith and Lynne Naylor for Nickelodeon. Originally produced by Spümcø, the series aired on Nickelodeon from August 11, 1991, to December 16, 1995, with its last episode airing on MTV on October 20, 1996, spanning for a total of five seasons and 52 episodes. The series follows the misadventures of Ren Höek, an emotionally unstable and psychotic chihuahua dog; and Stimpy, a good-natured and dimwitted Manx cat. It is the third to be aired of the original three Nickelodeon animated series known as "Nicktoons", alongside Doug and Rugrats, and is considered to be one of the progenitor series of the brand.

The Ren & Stimpy Show has received widespread critical acclaim from critics and audiences, with praise going to its visuals, animation, and surreal nature. However, it has also generated significant controversy for its dark humor, adult humor, violence, and shock value. This controversy contributed to the production staff's altercations with Nickelodeon's Standards and Practices department, in addition to Spümcø's failure to deliver episodes on time, all of which led to Kricfalusi's termination from the show in 1992. Games Animation would produce the remaining three seasons of the series, during which it received criticism of a perceived decline in quality. One episode was banned from ever airing on Nickelodeon, while three were initially left unaired in North America until it was broadcast on MTV, one on January 13, 1993 and two on October 20, 1996.

A reboot for adult audiences, Ren & Stimpy "Adult Party Cartoon", was produced by Kricfalusi and Spümcø and aired in 2003 on Spike TV. Only three episodes were aired before the series was canceled due to both production delays and negative critical reception from both critics and fans of the original series, with three additional episodes (all incomplete at the time of the cancellation) being released straight to DVD in 2006.

On August 5, 2020, Comedy Central announced that they had ordered a second reboot of the series to be produced without the involvement of Kricfalusi.