The Costumes Are A-Changin'

 is a Halloween episode of The Grim Adventures of Billy, Mandy, Felicity, and Toby.

Summary
Everyone in Endsville turn into whatever costume they're wearing and are now cursed by Circe's magical spell.

Cast

 * Greg Eagles as Grim
 * Richard Steven Horvitz as Billy
 * Grey DeLisle as Mandy
 * Eden Sher as Felicity
 * Max Charles as Toby
 * Laura Bailey as Kaitlyn
 * Kate Miccuci as Brielle
 * Phil LaMarr as Declan
 * Ashley Johnson as Sonnet

Trivia

 * Costumes:
 * Felicity - Vampire
 * Kaitlyn - 18th Century princess
 * Brielle - Goth Lolita
 * Sonnet - leopard girl
 * Declan - werewolf