Underfist: Halloween Bash Irwin, Hoss Delgado, Jeff the Spider, Fred Fredburger, and General Skarr from the "Grim Adventures of Billy and Mandy" team up to fight an evil candy army from the Underworld on Halloween. Details Casts Videos Galleries Posters Title Underfist: Halloween Bash Release Date 2008-10-12 Runtime 01 Hours 01 Minutes Genres Action Comedy Family Fantasy Animation TV Movie Production Companies Cartoon Network Studios Production Countries Grey DeLisle... Mandy / Aunt Sis / Kid / ... Greg Eagles... Grim / Sperg / Giant Cand... Richard Steven Horvitz... Billy / Harold / Pumpkin ... Vanessa Marshall... Irwin / Hoss's Mom (voice... Diedrich Bader... Hoss Delgado (voice)... Armin Shimerman... General Skarr / Candy Ske... C.H. Greenblatt... Fred Fredburger (voice)... Maxwell Atoms... Jeff the Spider (voice)... Phil LaMarr... Dracula / Grandmama / Bou... Rachael MacFarlane... Mindy (voice)... Dave Wittenberg... Bun-Bun / Trick-or-Treate... Dan Gilvezan... Confic / Humicun (voice)... Greg Ellis... Perkins / Peanutbutter Wh... Jess Harnell... Singer (voice)... Martin Jarvis... Nergal / Police Officer /... Underfist: Halloween Bash promo (2008) (Teaser) Original Size (1280x720) Original Size (1280x720) Original Size (1280x720) Original Size (3840x2160) Original Size (1504x846) Original Size (2000x3000) Original Size (2000x3000) Original Size (845x1267) Original Size (2000x2822)