Kevin Costner's Horizon: An American Sagais an ambitious passion project for the actor/filmmaker, but Costner's best movie of the 2000s feels like it was already establishing the kind of story he wanted to tell. Costner's career in the Western genre has largely defined him as an actor, with one of his breakout roles coming in Silverado, winning Oscars for his directorial debut in Dances with Wolves, playing Old West icon Wyatt Earp, and even starring in the neo-Western series Yellowstone.