Robert Taylor as Marcus Vinicius

Deborah Kerr as Lygia

Leo Genn as Petronius

Peter Ustinov as Nero

Patricia Laffan as Poppaea

Finlay Currie as Peter

Abraham Sofaer as Paul

Marina Berti as Eunice

Buddy Baer as Ursus

Felix Aylmer as Plautius

Nora Swinburne as Pomponia

Ralph Truman as Tigellinus

Norman Wooland as Nerva

Peter Miles as Nazarius

Geoffrey Dunn as Terpnos

Nicholas Hannen as Seneca

D.A. Clarke-Smith as Phaon

Rosalie Crutchley as Acte

John Ruddock as Chilo

Arthur Walge as Croton

Elspeth March as Miriam

Strelsa Brown as Rufia

Alfredo Varelli as Lucan

Roberto Ottaviano as Flavius

William Tubbs as Anaxander

Pietro Tordi as Galba

Marika Aba as Dancer at Nero's Banquet (uncredited)

Adriano Ambrogi as Wine Bibber (uncredited)

Anna Arena as Woman (uncredited)

Alfred Baillou as Christian Prisoner in Arena (uncredited)

Giacomo Barnas as Senator (uncredited)

Scott R. Beal as Fisherman (uncredited)

John Binns as Officer (uncredited)

Francesca Biondi as Slave Girl (uncredited)

Carlo Borelli as Noble (uncredited)

Leslie Bradley as Hasta (2nd Praetorian) (uncredited)

Alfred Brown as Man (uncredited)

Valentino Bruchi as Mirmillon (uncredited)

Dante Ciriaci as Wine Bibber (uncredited)

Frank Colson as Man (uncredited)

Adrienne Corri as Young Christian Girl (uncredited)

Luca Cortese as Old Man (uncredited)

David Craig as Little Boy (uncredited)

Daniel de Jonghe as Apostle (uncredited)

Liana Del Balzo as Woman (uncredited)

Jack Del Rio as Apostle (uncredited)

Lia Di Leo as Pedicurist (uncredited)

Franco Fantasia as Man (uncredited)

Cesare Fasulo as Noble (uncredited)

Al Ferguson as Apostle (uncredited)

Enzo Fiermonte as Mounted Captain (uncredited)

Enrico Formichi as Man with Wine Cup (uncredited)

John Fostini as Young Unbaptized Man (uncredited)

Dino Galvani as Senator (uncredited)

Richard Garrick as Slave (uncredited)

Jack George as Fisherman (uncredited)

Carlo Ghisini as Guard (uncredited)

Trudy Glassford as Woman (uncredited)

Joan Griffiths as Woman (uncredited)

Robin Hughes as Christ (voice) (uncredited)

Adam Jennette as Man (uncredited)

Philip Kieffer as Apostle (uncredited)

Gipsy Kiss as Slave Girl (uncredited)

Lee Kresel as Man (uncredited)

Richard Larke as Guard (uncredited)

Sophia Loren as Lygia's Slave (uncredited)

Giovanni Lovatelli as Banquet Man (uncredited)

Helena Makowska as Older Woman (uncredited)

Anna Mancini as Nubian Slave Girl (uncredited)

Michael Mark as Fisherman (uncredited)

Clelia Matania as Parmenida (uncredited)

Richard McNamara as Legionnaire (uncredited)

Harriet Medin as Woman (uncredited)

Dario Michaelis as Lydia's Guard (uncredited)

Ernesto Molinari as Fisherman (uncredited)

John Myhers as Guard (uncredited)

Vincent Neptune as Apostle (uncredited)

Anna Maria Padoan as Young Unbaptized Woman (uncredited)

Louis Payne as Apostle (uncredited)

Walter Pidgeon as Narrator (voice) (uncredited)

Aldo Pini as Headkeeper (uncredited)

Alberto Plebani as Steward (uncredited)

Paola Quattrini as Crying Girl (uncredited)

Dino Raffaelli as Man (uncredited)

George Restivo as Apostle (uncredited)

Alfredo Rizzo as Hairdresser (uncredited)

Amerigo Santarelli as Guard Tying the Christians (uncredited)

Leonardo Scavino as Man (uncredited)

Alessandro Serbaroli as Officer (uncredited)

Bud Spencer as Imperial Guard (uncredited)

Raffaele Tana as Man (uncredited)

Elizabeth Taylor as Christian Prisoner in Arena (uncredited)

William Taylor as Guard Captain / Marcus' Guard (uncredited)

Michael Tor as Centurian (uncredited)

Giuseppe Tosi as Wrestler (uncredited)

Carlo Tricoli as Apostle (uncredited)

Renato Valente as Guard (uncredited)

Scilla Vannucci as White Slave Girl (uncredited)

Giuseppe Varni as Hairdresser (uncredited)

Dianora Veiga as Slave Girl (uncredited)

Harry J. Vejar as Fisherman (uncredited)

Romilda Villani as Slave Girl (uncredited)

Maria Zanoli as Woman (uncredited)

Christopher Lee as Chariot Driver (uncredited)