Although gladiator fights were officially banned by Constantine the Great in the year 325 CE they were held until 404 CE. That year, on January 1, the Western Roman Emperor Honorius finally and irrevocably abolished these bloody games.
He did so after the monk Almachius appeared in the arena wanting to stop the gladiator fight, and who was stoned by the feral crowd eager for bloody entertainment.
Chariot races, on the other hand, although they were criticized by Christian writers, continued until 549 CE.