There was no imitating William Holden, and in Hollywood that may be the sincerest form of flattery.

The impressionists did Bogart, Gable, Stewart, Fonda and lately the politicians. But William Holden -- who made 70 movies, from "Golden Boy" in 1939 to "S.O.B.," Blake Edwards' 1981 satire of Hollywood -- was never in anybody's repertoire of mannerisms.

He didn't have any. He could act.

Oh, there is no secret about what he was. Holden, who was found dead yesterday in his Santa Monica, Calif., home at the age of 63, was the robust all-American leading man who looked good in a tuxedo ("Sunset Boulevard," 1950) or a uniform ("The Bridges at Toko-Ri," 1955) or with his shirt off ("Picnic," 1956).

When he got older, he was cast as an older leading man ("Network," 1976). He had made a hit with his first picture, won the Oscar for best actor with "Stalag 17" in 1953 and never faded away or fell into the protection of "character roles."

But there was a side of William Holden that recurred in his films, to which directors cast and audiences responded. It was an attitude, a stance, a vantage point that may be peculiarly American, though it coexists uneasily with our gunpowder-and-whiskey frontier tradition.

Holden often played characters who were afraid of what they had to do, but who went ahead and did it anyway. He seemed to give those roles a psychological depth and an attending vulnerability that set them apart.

If James Garner, in "The Americanization of Emily" and his "Maverick" TV series, has been a paragon of the all-American wise-guy chicken, and John Wayne our chief exemplar of nationalistic swagger, Holden projected something else.

Whether as a lover or a fighter, he always seemed to face a choice. You could see it in his forehead and in the way he walked, which was with a certain heaviness of stride. He was choosing, in the way Americans -- unburdened by ancient codes -- are required to.

In a marvelous Carol Reed film of 1958 titled "The Key," he played a World War II tugboat skipper who inherits the lady friend (Sophia Loren) when fellow captain Trevor Howard is killed in action. Loren's closet is filled with the uniforms of previous doomed skipper-lovers, and she is fatalistic.

Holden is not. Ordered to sea and certain death, he doesn't want to go. He stamps and rages. But he goes. When his tug is torpedoed, he stamps his feet in an outraged fury that is close to panic. But he carries on. No stiff upper lip, just an individual who wants to survive.

That same year saw "The Bridge on the River Kwai," in which Holden played an odd-lot American sailor caught up in a battle of ancient military codes, both British and Japanese. He was scared to death, but gallant.

In "The Bridges at Toko-Ri," a film which came out in the middle of the Korean Conflict, Holden portrayed an American carrier pilot haunted by the specter of dangerous bombing missions. As a jet fighter pilot, he was the warrior hero of the modern age, yet he made no attempt to hide his overwhelming fear from his wife, played by Grace Kelly. He didn't want to die, but he fulfilled his mission.

His best-known role was probably that of Sefton, the cynical, wisecracking sergeant of Billy Wilder's "Stalag 17." The American flyers in that German prison camp were funny and sad and deceived, and the skewed sense of duty fit him like a glove on a hand.

He was also, of course, a movie star and a genuinely handsome one at that. In "Picnic," draped over by Kim Novak and with lunch spread on the grass and George Durning's pretty "Moonglow" theme in the air, Holden caused pulse rates to increase in theaters all over the land.

In his first film, "Golden Boy," he played a boxer who really wanted to be a violinist, and in "The World of Suzie Wong" (1960) he played a businessman who had given himself one year in Hong Kong to try to prove himself as a painter and artist. He was tough, but he had dreams.

A Paramount executive said this about Holden upon signing him to a 14-year contract:

"Love-starved women will never yearn to have Holden crush them in his arms like Valentino, but a housewife will watch Holden in a romantic scene and then nudge her husband and say, 'Honey, he reminds me of you.' "

Men liked him, too. He was reported not to have a swelled head. He explained that producers simply decided: "If we can't get Gable or Wayne, we can always get Holden."

William Holden did not gain credibility or character as he got older. He'd had it all along, and he never lost it. By 1974, he was able to make even the architect in "The Towering Inferno" a sympathetic character, and by "Network" he was still making choices -- in this case the thoroughly emotional one to leave his loyal wife for the uncertainties of love with a glamorpuss.

In "S.O.B.," an often mean-spirited film that was his last, he played a nice guy.

It was only a movie. But he played it well.