1. Gunfight at the O.K. Corral (1957)

A quintessential Western, Douglas plays Doc Holliday opposite Burt Lancaster’s Wyatt Earp. Their uneasy alliance leads to the infamous shootout, dramatized with gripping intensity. Douglas brings depth to Holliday, portraying him as both reckless and loyal. The film’s sharp dialogue, stellar performances, and historical weight make it an undisputed classic, securing its place as Douglas’s greatest Western.