 Fredric MarchMarcus Superbus - Prefect of Rome | Marcus Superbus - Prefect of Rome |
 Elissa LandiMercia | Mercia |
 Claudette ColbertEmpress Poppaea | Empress Poppaea |
 Charles LaughtonEmperor Nero Claudius Caesar | Emperor Nero Claudius Caesar |
 Ian KeithTigellinus | Tigellinus |
 Arthur HohlTitus | Titus |
 Harry BeresfordFavius Fontelas | Favius Fontelas |
 Tommy ConlonStephan | Stephan |
 Ferdinand GottschalkGlabrio | Glabrio |
 Vivian TobinDacia | Dacia |
 William V. MongLicinius | Licinius |
 Joyzelle JoynerAncaria | Ancaria |
 Richard AlexanderViturius | Viturius |
 Nat PendletonStrabo | Strabo |
 Clarence BurtonServillius | Servillius |
| HHarold HealyTybul | Tybul |
 Robert SeiterPhilodemus | Philodemus |
 Charles MiddletonTyros | Tyros |
 Henry BrandonColosseum Spectator (uncredited) | Colosseum Spectator (uncredited) |
 John CarradineChristian Martyr / Gladiator Leader / Voice in Coliseum Mob (uncredited) | Christian Martyr / Gladiator Leader / Voice in Coliseum Mob (uncredited) |
 Dave O'BrienChristian on Stairway (uncredited) | Christian on Stairway (uncredited) |
 Sally RandCrocodiles' Victim (uncredited) | Crocodiles' Victim (uncredited) |
 Arthur ShieldsChaplain Costello (1944 Re-Release Prologue) (uncredited) | Chaplain Costello (1944 Re-Release Prologue) (uncredited) |
 Tom TullyHoboken (1944 Re-Release Prologue) (uncredited) | Hoboken (1944 Re-Release Prologue) (uncredited) |
 Lionel BelmoreBettor of 300 Silver | Bettor of 300 Silver |
 Ynez SeaburyLittle Girl | Little Girl |
