William Forsythe as John Wayne Gacy

Jesse Moss as Jason Moss

Emma Lahana as Alyssa

Cole Heppell as Alex Moss

Belinda Metz as Valerie Moss

Michael Ryan as Frank Moss

Eric Keenleyside as Stan

Daryl Shuttleworth as Guard Thompson

Patrick Gilmore as Glen Phillips

Andrew Airlie as Professor Harris

Michael Kopsa as FBI Agent

Jeffrey Bowyer-Chapman as Male Hustler

Hunter Elliott as Butcher Shop Victim

Michaela Mann as Prostitute

Dee Jay Jackson as Desk Guard

Libby Osler as Counter Girl

Brett Dier as Marcus

James Ralph as Armed Guard

Jaren Brandt Bartlett as Mike

Lynn Colliar as TV News Reporter

Richard Harmon as Victim

Andrea Brooks as Stalked Girl

Anthony Shim as Paul

Karissa Tynes as Amy

Josh Goring as Marcus' Friend (uncredited)

Kai Kennedy as Bobby (uncredited)

John Andrew Vaas as Undercover Detective (uncredited)