A gladiator (Latin: gladiator, "swordsman", from gladius, "sword") was an armed combatant who entertained audiences in the Roman Republic and Roman Empire in violent confrontations with other gladiators, wild animals, and condemned criminals. Some gladiators were volunteers who risked their lives and their legal and social standing by appearing in the arena. Most were despised as slaves, schooled under harsh conditions, socially marginalized, and segregated even in death.

Irrespective of their origin, gladiators offered spectators an example of Rome's martial ethics and, in fighting or dying well, they could inspire admiration and popular acclaim. They were celebrated in high and low art, and their value as entertainers was commemorated in precious and commonplace objects throughout the Roman world.

The origin of gladiatorial combat is open to debate. There is evidence of it in funeral rites during the Punic Wars of the 3rd century BC, and thereafter it rapidly became an essential feature of politics and social life in the Roman world. Its popularity led to its use in ever more lavish and costly games.

The gladiator games lasted for nearly a thousand years, reaching their peak between the 1st century BC and the 2nd century AD. Christians disapproved of the games because they involved idolatrous pagan rituals, and the popularity of gladatorial contests declined in the fifth century, leading to their disappearance.