Ellen Burstyn - Chris MacNeil

Max von Sydow - Father Merrin

Lee J. Cobb - Lt. William Kinderman

Kitty Winn - Sharon

Jack MacGowran - Burke Dennings

Jason Miller - Father Karras

Linda Blair - Regan

William O'Malley - Father Dyer (as Reverend William O'Malley S.J.)

Barton Heyman - Dr. Klein

Peter Masterson - Dr. Barringer - Clinic Director (as Pete Masterson)

Rudolf Schündler - Karl

·Gina Petrushka - Willi

·Robert Symonds - Dr. Taney

·Arthur Storch - Psychiatrist

·Thomas Bermingham - Tom - President of University (as Reverend Thomas Bermingham S.J.)

·Vasiliki Maliaros - Karras' Mother

·Titos Vandis - Karras' Uncle

·John Mahon - Language Lab Director

·Wallace Rooney - Bishop Michael

·Ron Faber - Chuck - Assistant Director / Demonic Voice

·Donna Mitchell - Mary Jo Perrin

·Roy Cooper - Jesuit Dean

·Robert Gerringer - Senator at Party

·Mercedes McCambridge - Demon (voice)

·Paul Bateson - Radiologist's Assistant

·Elinore Blair - Nurse

William Peter Blatty - The Producer

·Mary Boylan - First Mental Patient

·Dick Callinan - Astronaut

·Mason Curry - Doctor (voice)

·Toni Darnay - Violent psychotic patient

·Eileen Dietz - Pazuzu's Face

·Joanne Dusseau - Senator's Wife

·Bernard Eismann - Minor Role

·Beatrice Hunter - Minor Role

·Yvonne Jones - Bellevue Nurse

·Don LaBonte - Minor Role

·Ann Miles - Spiderwalk

·John Nicola - Priest

·Vincent Russell - Subway Vagrant

·Gerard F. Yates - Priest Singing Around Piano at Party

·Elton LeBlanc - Elderly Man at Apartment