- Jeannie Elias - Malaria
- Alan Oppenheimer - Father Time
- Keone Young - Kwan Ti
- Wayne Knight - Jack O'Lantern
- Scott Menville - Pinocchio
- Mary Jo Catlett - Witch
- Frank Welker - Scooby-Doo (voice)
- Frank Welker - Boskov
- Fred Willard - Boogey
- Dawnn Lewis - Grim's Granny
- Rob Paulsen - Tooth Fairy
- Jane Carr - Pud'n
- Diedrich Bader - Hoss Delgado
- Diedrich Bader - Hoss Delgado (voice)
- Brian Tochi - Chef
- David Warner - Nergal (voice)
- Rachael MacFarlane - Eris
- Rachael MacFarlane - Mindy
- Rachael MacFarlane - Eris (voice)
- Billy West - Viper
- Billy West - The Nerve
- Billy West - Guard
- Phil LaMarr - Hector Con Carne
- Phil LaMarr - Dracula
- Phil LaMarr - Judge Roy Spleen (voice)
- Dee Bradley Baker - Mandy's Dad
- Dee Bradley Baker - Announcer
- Dee Bradley Baker - Worm
- James Arnold Taylor - Fred Flintstone
- Jennifer Hale - Gladys (voice)
- Jennifer Hale - Gladys
- Nika Futterman - Pandora
- Martin Jarvis - Nergal
- Maxwell Atoms - Jeff the Spider (voice)
- Armin Shimerman - General Skarr
- Henry Gibson - Lord Pain
- John Vernon - Dean Toadblatt
- Candi Milo - Grim's Mom (voice)
- Candi Milo - Guillermo (voice)
- 'Weird Al' Yankovic - Squid Hat
- C.H. Greenblatt - Fred Fredburger (voice)
- Debi Derryberry - Nergal Jr.
- Jake Thomas - Nigel Planter
- Tom Kane - Professor Utonium
- Tom Kane - Captain Heifer
- Ronnie Schell - Dean Toadblatt
- John Kassir - Lord Moldybutt
- Laraine Newman - Crossing Guard (voice)
- Cree Summer - Cave Witch (voice)
- R. Lee Ermey - Sergeant / Drill Sergeant
- Michael Dorn - King Beardbottom / Clown / Dwarf #2
- Jennifer Darling - Pollywinkle (voice)
- Malcolm McDowell - Baron Von Ghoulish
- Carol Kane - Mrs. Claus
- Gilbert Gottfried - Santa Claus
- Brian A. Miller
- Jay Bastian
- Drew Neumann
- Gregory Hinde
David Warner hace el papel de Nergal (voice).
Michael Dorn interpreta a King Beardbottom / Clown / Dwarf #2 en la serie.
Wayne Knight interpreta a Jack O'Lantern en la serie.
Greg Eagles hace el papel de Grim (voice).
Richard Steven Horvitz interpreta a Billy (voice) en la serie.
Grey DeLisle hace el papel de Mandy (voice).
Vanessa Marshall interpreta a Irwin (voice) en la serie.
Capítulo disponible en las siguientes plataformas:
