When Ronald Reagan announced his candidacy for governor of California—or so the story goes—somebody wisecracked, “Reagan for governor? No, Jimmy Stewart for governor. Reagan for best friend.” In later years Ronald Reagan would be referred to as a former film star, but in truth he was never really a star. In A-list films he was a costar; he was a star of sorts in B movies, competing with actors like Rory Calhoun for leads in second-level Westerns.

But he was a good costar and a good B-movie leading man, and he had, in certain roles, a scrappy Irish working-class charm that put a charge in a movie. His most famous part, as George Gipp, the salty, pool-hustling football player in Knute Rockne—All-American (1940, directed by Lloyd Bacon), hardly amounted to the status of costar. He is gone about halfway through the movie, but he makes a real impression while he’s there, a fine complement to Pat O’Brien’s powerhouse Rockne. As George Armstrong Custer in Santa Fe Trail (also 1940, directed by Michael Curtiz), he is a lightweight, a pale shadow of Errol Flynn’s charismatic Jeb Stuart. Compare his Custer with Flynn’s the next year in Raoul Walsh’s They Died With Their Boots On to see the difference between a leading man and a costar.

Reagan’s biggest hit was Kings Row (1942), a soap opera about small-town corruption in which his character awakens after an operation to find his legs have been amputated and exclaims the famous line “Where’s the rest of me?” (It was his second most famous bit of dialogue after his deathbed “Win one for the Gipper” speech in Rockne .) It’s the only dialogue in Kings Row worth recalling; the film has not held up well, largely because Robert Cummings’s performance in the lead is so bland he makes Reagan seem like . . . well, like Errol Flynn.

There’s so little substantial film work in Reagan’s résumé that if not for stints as the host and sometime actor on “General Electric Theater” (1954–61) and later on “Death Valley Days” in the mid-1960s, it’s doubtful he’d be remembered as an actor at all. Perhaps his biggest success as a leading man came in 1951 with Bedtime for Bonzo , though in truth it’s not easy to tell who was doing the lead acting, Reagan or the chimpanzee his college professor is experimenting with. His low-budget Westerns in the 1950s scarcely made an impression. He played Wyatt Earp in Law and Order (1953), a remake of a Walter Huston film that wasn’t bad, but Cattle Queen of Montana (1954), which put him opposite Barbara Stanwyck, showed how little weight he carried when faced off with a strong leading lady.

And then, at the very end of his acting career, Reagan not only