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