 Ellen BurstynChris MacNeil | Chris MacNeil |
 Linda BlairRegan MacNeil | Regan MacNeil |
 Jason MillerFather Damien Karras | Father Damien Karras |
 Max von SydowFather Lankester Merrin | Father Lankester Merrin |
 Lee J. CobbLt. Bill Kinderman | Lt. Bill Kinderman |
 William O'MalleyFather Joseph Kevin Dyer | Father Joseph Kevin Dyer |
 Kitty WinnSharon Spencer | Sharon Spencer |
 Barton HeymanDr. Klein | Dr. Klein |
 Peter MastersonDr. Barringer | Dr. Barringer |
 Jack MacGowranBurke Dennings | Burke Dennings |
 Rudolf SchündlerKarl | Karl |
| GGina PetrushkaWilli | Willi |
 Robert SymondsDr. Taney | Dr. Taney |
| AArthur StorchPsychiatrist | Psychiatrist |
| TThomas BerminghamTom | Tom |
 Vasiliki MaliarosMary Karras | Mary Karras |
 Titos VandisUncle John | Uncle John |
 John MahonLanguage Lab Director | Language Lab Director |
 Wallace RooneyBishop Michael | Bishop Michael |
 Ron FaberChuck / Demon (voice) | Chuck / Demon (voice) |
 Donna MitchellMary Jo Perrin | Mary Jo Perrin |
 Roy CooperJesuit Dean | Jesuit Dean |
 Robert GerringerSenator at Party | Senator at Party |
 Mercedes McCambridgeDemon (voice) | Demon (voice) |
| PPaul BatesonRadiologist's Assistant (uncredited) | Radiologist's Assistant (uncredited) |
| EElinore BlairNurse (uncredited) | Nurse (uncredited) |
 William Peter BlattyThe Producer (uncredited) | The Producer (uncredited) |
 Mary BoylanFirst Mental Patient (uncredited) | First Mental Patient (uncredited) |
| DDick CallinanAstronaut (uncredited) | Astronaut (uncredited) |
| MMason CurryDoctor (voice) (uncredited) | Doctor (voice) (uncredited) |
