What was the first feature film based on a Cartoon Network original series?

The Powerpuff Girls Movie was the first feature film based on a Cartoon Network original series.

The 2002 theatrical release expanded Craig McCracken’s animated television creation into a feature-length origin story. Rather than simply assembling several television segments, the movie developed the girls’ creation, their early relationship with Professor Utonium, and the rise of Mojo Jojo.

The film’s position in Cartoon Network history is distinct from later television specials and direct-to-video projects. Dexter’s Laboratory: Ego Trip, for example, was a television film, while Steven Universe: The Movie arrived many years later and was made for television.

Its theatrical format made the movie an important experiment for the network’s original animation brand. The release also demonstrated that a Cartoon Network property could be expanded beyond short television stories into a feature-length narrative.