Anthony Quinn as Kiril Lakota

Laurence Olivier as Piotr Ilyich Kamenev

Oskar Werner as Fr. David Telemond

David Janssen as George Faber

Vittorio De Sica as Cardinal Rinaldi

Leo McKern as Cardinal Leone

John Gielgud as The Elder pope

Barbara Jefford as Dr. Ruth Faber

Rosemary Dexter as Chiara

Frank Finlay as Igor Bounin

Burt Kwouk as Chairman Peng

Arnoldo Foà as Gelasio (as Arnoldo Foa')

Paul Rogers as Augustinian

George Pravda as Gorshenin (credit only)

Clive Revill as Tovarich Vucovich

Niall MacGinnis as Capuchin Monk

Marne Maitland as Cardinal Rahamani

Isa Miranda as The Marchesa

Gerald Harper as Brian

Leopoldo Trieste as Dying Man's Friend

Peter Copley as English Cardinal

Arthur Howard as English Cardinal

Jean Rougeul as Dominican

Arnaldo Caivano as Dying Man (uncredited)

Inna Alexeievna as Party Guest (uncredited)

Silvana Bacci as Party Guest (uncredited)

John Frederick as American Cardinal (uncredited)

Åke Lindman as Soldier Releasing Lakota (uncredited)

Lex Monson as Third African Priest (uncredited)

Dom Moor as Polish Cardinal (uncredited)

Antonio Proietti as Cardinal (uncredited)

Alfred Thomas as African Cardinal (uncredited)