19 images of the Underfist: Halloween Bash cast of characters. It aired on October 12, 2008. Underfist: Halloween Bash is an American animated spin-off special of The Grim Adventures of Billy & Mandy.

Directed by Shaun Cashman. Photos of the Underfist: Halloween Bash (Show) voice actors. With Grey Griffin, Greg Eagles, Richard Steven Horvitz, Vanessa Marshall.

Irwin, Hoss Delgado, Jeff the Spider, Fred Fredburger, and General Skarr from the "Grim Adventures of Billy and Mandy" team up to fight an … Underfist, also called Underfist: Halloween Bash is an animated special of The Grim Adventures of Billy & Mandy meant to be setup for a Spin-Off of the show, but the project never went through due to Maxwell Atoms' contract with Cartoon Network expiring.

Underfist: Halloween Bash (TV Movie 2008) cast and crew credits, including actors, actresses, directors, writers and more.