Planet Hulk
After being exiled from Earth by the Illuminati, Hulk found himself on the planet Sakaar, where he was imprisoned and forced to do gladiatorial battle in the emperor's arena. Hulk and his compatriots quickly rose through the ranks, and were soon approached by a rebellion that plotted to overthrow the emperor. Hulk declined, and the rebels were detained. But rather than killing them in the arena, Hulk helped them escape, and led his fellow gladiators to freedom.