The Trope: Every gladiator who entered an arena was an enslaved man who battled to the death.
Why Is It Inaccurate? Despite being banned from the arena in 200 AD, Roman law initially allowed women to fight other women in spectator battles. And while the events began with criminal executions, professional gladiators rarely lost their lives.
Ancient Romans treated their fighters much like modernday boxers and mixed martial arts fighters, and had referees that ensured a fair fight. Fatalities certainly occurred, but many gladiators who lost their lives did so because they either gave up or weren't pardoned by the Emperor after losing the battle.
Because Romans treated these fighters like professional athletes, many free men and women chose to attend Gladiator schools to train and fight in arenas and amphitheaters.
Notable Offenders: Gladiator, Spartacus, Rome (series)