Fredric March as Marcus Superbus - Prefect of Rome

Elissa Landi as Mercia

Claudette Colbert as Empress Poppaea

Charles Laughton as Emperor Nero Claudius Caesar

Ian Keith as Tigellinus

Arthur Hohl as Titus

Harry Beresford as Favius Fontelas

Tommy Conlon as Stephan

Ferdinand Gottschalk as Glabrio

Vivian Tobin as Dacia

William V. Mong as Licinius

Joyzelle Joyner as Ancaria

Richard Alexander as Viturius

Nat Pendleton as Strabo

Clarence Burton as Servillius

Harold Healy as Tybul

Robert Seiter as Philodemus

Charles Middleton as Tyros

Henry Brandon as Colosseum Spectator (uncredited)

John Carradine as Christian Martyr / Gladiator Leader / Voice in Coliseum Mob (uncredited)

Dave O'Brien as Christian on Stairway (uncredited)

Sally Rand as Crocodiles' Victim (uncredited)

Arthur Shields as Chaplain Costello (1944 Re-Release Prologue) (uncredited)

Tom Tully as Hoboken (1944 Re-Release Prologue) (uncredited)

Lionel Belmore as Bettor of 300 Silver