Billy's Balloon is a 16 mm animated short by Don Hertzfeldt. It was his fourth and final student film at UC Santa Barbara. Similar to his other cartoons, he uses a minimalist stick-figure technique.

The film was invited into Official Competition at the 1999 Cannes Film Festival (where Hertzfeldt was the youngest director involved), and it won the Grand Jury Award at the 1999 Slamdance Film Festival.

On top of its film festival runs (and subsequent popularity online), the short has also appeared on Adult Swim and MTV in the US and on a number of international TV broadcasts around the world. Hertzfeldt has noted that the short's international popularity is likely because it has no dialogue and plays like a silent film.