Atrocia was the stage-name of an Endsville TV show Horror-Hostess, whose TV show was presented in a studio near by both Billy's and Mandy's houses. Atrocia made her first appearance in Grim or Gregory?, during season 1. In her first appearance, Grim is observed as having a crush on Atrocia, the TV Horror show Hostess who was presenting an all-night Halloween TV Marathon that Grim was watching on Halloween when Billy and Mandy both demand that Grim accompany them Trick or Treating. Her character proved to be a popular Halloween costume for the mother of a kid out trick-or-treating that night.