John Callahan's Quads! (or simply Quads!) is an adult cartoon produced by Nelvana. It was created by and based upon the work of John Callahan, who also created another Nelvana-produced cartoon, Pelswick. The show aired on Teletoon at Night in Canada, SBS in Australia, and in Latin America on Locomotion and Adult Swim. The show never aired in the United States; however, the series was released on YouTube in 2018. This was the first show animated completely using the Macromedia Flash software, then came Max & Ruby, another Canadian show made by Nelvana, and finally, ¡Mucha Lucha! became the first of its kind for American television.

It was produced by Animation Works, Nelvana Limited, Media World Features, SBS Independent, and Film Victoria, with support from ScreenWest and the Lotteries Commission of Western Australia. It was first aired on Teletoon at Night on February 2, 2001.When Quads Won't Leave was an early title for the cartoon.