Brian Dennehy

as John Wayne Gacy

Michael Riley

as Joe 'Polock' Kozenczak

Margot Kidder

as Rachel Grayson

Meg Foster

as Linda Carlson

Martin Julien

as Ted Koslo

Scott Hylands

as Mike Paxton

John Boylan

as Atkins

David Eisner

as Williams

Tony De Santis

as DeMarco

Mark Humphrey

as King

Gary Reineke

as Petrie

Tim Progosh

as Morris

Danny Pawlick

as Santori

Bruce Ramsay

as Bragg

Brenda Bazinet

as Alice Pearson

Liliane Clune

as Marcia Kozenczak

Toby Proctor

as Michael Kozenczak

Christopher Marren

as Billy

Gerry Quigley

as Walden

Nicholas Pasco

as Barton

Michael Copeman

as Chief Cameron

James Kee

as Hoskins

Brigette Lawson

as Pam

Jay Brazeau

as Jake Burns

Cynthia Preston

as Cindy Beck

Andrew Gillies

as Vincent Austin

Kurt Reis

as Waldron

Judith Goodwin

as Mrs. Gant

Shawn Lawrence

as Mr. Gant

Jacqueline Graham

as Lorna Gant

Nicholas Shields

as Christopher Gant

Sarah Gibney

as Lisa Kozenczak

Aviva Magner

as Debbie Kozenczak

Maureen McRae

as Mrs. Trask

Timm Zemanek

as Mr. Trask

Maria Ricossa

as Helen Gacy

Darryl Palmer

as Sheriff

Peter Langley

as Mr. Miklovich

John Friesen

as Detective #1

Ray Paisley

as Illinois K-9 Officer

Brett Halsey

as Stan Wilder

Elliott Smith

as Gas Station Attendant

David Gardner

as Judge

David Bolt

as Asst. Principal Burke

Thomas Hauff

as Foreman Hendricks

David McAree

as Older Worker

J. Winston Carroll

as Sergeant on Wabash Ave.

Don Ritchie

as Detective on Shakespeare Ave.

Rudy Webb

as Cemetery Staffer

Robbie Rox

as Cicero Bar Owner

Larry Reynolds

as Finger Lake Proprietor

Veliko Pajkovic

as Man at Bus Station

John Granik

as Narrator (voice)

Luis Guzmán

as Waiter (uncredited)

Peter Kerenyi

as Pool Player (uncredited)