John Callahan's Quads! (or simply Quads!) is an adult animated television series 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's Adult Block 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 one of the first shows animated completely using the Macromedia Flash software.

It was produced by Animation Works, Nelvana, Media World Features, SBS Independent, and Film Victoria, with support from ScreenWest and Lotterywest. It was first aired on Teletoon at Night on 2 February 2001.

When Quads Won't Leave was an early title for the cartoon.