Underfist: Halloween Bash
Underfist: Halloween Bash is a 2008 animated TV movie based on The Grim Adventures of Billy & Mandy and was supposed to be a pilot for an unfinished show.
A marshmallow bunny named Bun Bun has taken over Endsville. Irwin, Jeff, General Skarr, Hoss Delgado and Fred Fredburger form the group known as Underfist.
- Vanessa Marshall as Irwin
- Maxwell Atoms as Jeff
- Armin Shimerman as General Skarr
- Diedrich Bader as Hoss Delgado
- C.H. Greenblatt as Fred Fredburger
- Rachael MacFarlane as Mindy