When he came into town three years ago, it was to sit in front of a Peerless Home Water Filter. He was the official spokesman for this shiny appliance, and although he never said a word about it, and in fact never looked down at the table where it lay, the device nevertheless gained a certain dignity by association.

The water filter came toward the end of his life, but Clarence Linden Crabbe had discovered much earlier that we do not cast ourselves in our roles, we only perform them. He had planned to become a lawyer and wound up as Flash Gordon.

Buster Crabbe died Saturday at 74, after a heart attack in his home city of Scottsdale, Ariz. His roles--Billy the Kid, Tarzan and Captain Gallant of the Foreign Legion among them--had made him famous, but after a while, fame had not quite known what to do with him. By 1950, despite his 175 B-grade movies and the nickname "King of the Serials," he seldom was recognized on the street. Flash Gordon's head was a dye-shock of gold, but the real Clarence Crabbe's hair was reasonable brown.

That would have been fine as far as Buster Crabbe was concerned: he had intended to finish law school at the University of California and then return to his native Hawaii to practice, play golf and ride a surfboard. "It was all set out for me," he had said.

In 1932, as a first-year law student, he entered the Olympics in Los Angeles and won the Gold Medal in the 400-meter freestyle. Paramount Studio scouts already had done screen tests on 20 athletes from the Olympic Village, and the win placed Crabbe among the finalists.

His screen test consisted of Crabbe, attired in a G-string, tossing a spear and a papier-ma che' rock and flexing his muscles. He had not taken it seriously, but when the film was shown to 25 secretaries, they voted him most alluring by 24 to 1. That was the end of lawyering and surfing, and the beginning of a life in the movies, and later out of them.

The lines were very deep in his face three years ago, lines etched by his own hale enthusiasm, and with his full head of gray-brown hair and thick mustache he looked theatrically zestful. He was 72 then, but you could see what set him apart, and why a water filter would be placed in front of him. You could feel it in the way he grabbed your arm, squeezing to make a point, and how he seemed to absorb the energy in the room, beaming it back at double strength.

What the Peerless Faucet Co. had discovered that year was what Paramount Studios had discovered when he was 24 and dripping wet from the Olympic pool. He was not an actor, but a light source. His Flash Gordon was at all times a hawk-nosed, bare-chested American Olympic Swimmer pitted against Ming the Merciless. You would not want an actor to go up against Ming, anyhow. Better some Real Thing, however unlikely.

He knew he was not an actor. He had acknowledged, not exactly laughing, that his dramatic ability was said to have "risen to the point of incompetence, and then leveled off." He did not even believe he was handsome. "With this beak of a nose? No, no--dashing, that's the word for it. That's what Flash was."

By the time television arrived in the early 1950s, Buster Crabbe's film career had run down like an unwound clock, and he found himself neither a star nor a lawyer. It was television, though, that started him ticking once again, much to his own surprise: Asked to appear on a New York City station to introduce some old serials, he found that "after six weeks the cab drivers were saying 'Hi Flash' to me again."

He marketed swimming pools, wrote exercise books, made public appearances and accepted campy parts in which he was presented as a dramatic reminder of his former self. He appeared to be in grand health and full of beans, but was in fact puzzled by what had happened to him. In high school in Honolulu he had won 16 letters and was used to being taken note of early. He had willingly traded the law for a career as a hard-working contract actor, and then the contracts had expired. Fair enough. Yet at 72, he still felt "waylaid," he said.

Perhaps, through fame and famine, the hunger remained. In a letter written after a story on him had appeared in The Washington Post in 1980, he seemed sincerely flattered by the attention, reporting that "the flak from friends has been excellent."

There was about him that year--and this is something ineffable, an impression taken from a straightness of the back, a sharpness of speech, a guileless urge to correct--that advertised disclipline. He had kept his weight to within three pounds of his Olympic days, and had an iron handshake and a directness of expression. He was, he said, a Reagan man. He and Ronald Reagan had known each other in the old days. There was a resemblance between the men, too--the full head of hair, the weathered face, an optimism capable of surviving Hollywood. "But I'm not saying we were buddy-buddy," Crabbe had added quickly.

When he went on the nostalgia circuit, people often asked Buster Crabbe if "Flash Gordon" was "fun." It wasn't, he said. They shot 13-chapter serials in six weeks, working every day, 12 hours a day, and he was aware of the discontinuity and clumsy plot and no-rehearsal shooting, but he did it as well as he could, even if he would have liked to do it better. But "Flash Gordon" was a success.

He had said from time to time that he had never been given any decent roles, and wished he had been. But when people accept you for what you are, even if it is not what you intended it to be, it is not right to argue, and so Clarence Crabbe didn't. He started a swimming pool company.

In 1947 it was reported in several newspapers in eastern Europe that Buster Crabbe, having taken a stand against reactionary forces in Washington, D.C., had been machine-gunned to death on a New York street. Communist Party organs in Italy and Yugoslavia published long, fanciful obituaries, which Crabbe read with interest. By that year he had been largely forgotten, and news of his death reminded everyone that he still was alive.

He said he did not find the premature report of his death amusing, not at all.

But there was one element of the stories he liked: "The Communists said it took 43 bullets to knock old Flash Gordon down." He said he was flattered.