Kevin Costner was 23 in 1978, when he filmed his first feature, “Sizzle Beach, U.S.A.

,” also known as “Malibu Hot Summer.” That’s one fact. Another one: Kevin Costner looks right in a cowboy hat.

There’s more to movie stardom than that, but with Costner, the hat may have had something to do with the stardom, which came a few years after “Sizzle Beach/Malibu,” which came from Troma, the trash-forward, money-optional film production company behind “Class of Nuke ’em High” and “Surf Nazis Must Die.” Released in 1981, Costner’s debut feature follows three Los Angeles women, yearning for love, careers and meaning. The fifth-billed Costner plays the sole decent male in Southern California, a wealthy young stable owner sporting a cowboy hat.

The hat has the added benefit of hiding the actor’s modified bowl haircut, which has not stood the test of time. But the actor has. Ever since breaking through as the charismatic live wire Jake in his first real Western, director Lawrence Kasdan’s “Silverado” (1985), Costner has served as a genre ambassador and an advocate of the storytelling form.

Now 69, he recently spent four increasingly contentious seasons on “Yellowstone,” settling scores and clearing the horizon of varmints anywhere near the Dutton ranch. Now, as producer, co-writer, director and marquee attraction, Costner’s the largely self-financed force behind a four-film gamble known as “Horizon: An American Saga,” set in the Civil War er.