George C. Scott as Lt. William 'Bill' Kinderman

Ed Flanders as Father Joseph Kevin Dyer

Brad Dourif as James Venamun / The Gemini Killer

Jason Miller as Father Damien Karras / Patient X

Nicol Williamson as Father Morning

Scott Wilson as Dr. Temple

Nancy Fish as Nurse Allerton

George DiCenzo as Stedman

Don Gordon as Ryan

Lee Richardson as University President

Grand L. Bush as Sergeant Atkins

Mary Jackson as Mrs. Clelia

Viveca Lindfors as Nurse X

Ken Lerner as Dr. Freedman

Tracy Thorne as Nurse Keating

Barbara Baxley as Shirley

Zohra Lampert as Mary Kinderman

Harry Carey, Jr. as Father Kanavan

Sherrie Wills as Julie Kinderman

Edward Lynch as Patient A

Clifford David as Dr. Bruno

Alex Zuckerman as Korner Boy

Lois Foraker as Nurse Merrin

Tyra Ferrell as Nurse Blaine

James Burgess as Thomas Kintry

Kevin Corrigan as Altar Boy

Peggy Alston as Mrs. Kintry

John Durkin as Elderly Jesuit

Bobby Deren as Nurse Bierce

Jan Neuberger as Alice

Alexis Chieffet as Counter Attendant

Debra Port as Waitress

Walt MacPherson as Police Sergeant

David Dwyer as Second Police Officer

Danny Epper as Police Driver

William Preston as Old Man in Wheelchair

Chuck Kinlaw as Attendant

Demetrios Pappageorge as Casperelii

Nina Hansen as Little Old Lady

Samuel L. Jackson as Dream Blind Man

Shane Wexel as First Dream Boy (uncredited)

Ryan Paul Amick as Second Dream Boy (uncredited)

John Coe as Old Man in Dream (uncredited)

Jodi Long as First Dream Woman (uncredited)

Kathy Gerber as Second Dream Woman (uncredited)

Jan Smook as Radio Man (uncredited)

Amelia Campbell as Young Girl in Dream (uncredited)

Cherie Baron as Nurse

Larry King as Larry King

C. Everett Koop as Everett Koop

Patrick Ewing as Angel of Death

Clinton Brandhagen as Young Boy in Dream (uncredited)

Michael Criscuolo as Mental Patient (uncredited)

Cindy Cullom as Nurse (uncredited)

Colleen Dewhurst as Satan (voice) (uncredited)

Fabio as Angel (uncredited)

Randy Aaron Fink as Student (uncredited)

Jeff Henry as Angel (uncredited)

Patt Noday as Hospital Ward Priest (uncredited) (unconfirmed)

Manley Pope as Angel (uncredited)

John Thompson as John Thompson - Georgetown Hoyas Basketball Coach (uncredited)

Michael Tove as Man in Purgatory (uncredited)

Brad Waller as Asylum Inmate (uncredited)

Gary Wheeler as Crime Photographer (uncredited)

Teresa Wright as Penitent (uncredited)

Charles Edwin Powell as Patient X Possessed