Wasn't it women who used to have this problem? Being blond and having a gorgeous body and wanting to act and then finding, darn it, that people expected Styrofoam for brains and zero talent?

William Katt suffers similarly. He's been acting since his teens, has worked for Fosse and DePalma, has starred off-Broadway--and still he has to live down flying around in red Spandex on his television series "The Greatest American Hero," which was canceled last season. He works out at the gym four times a week, runs and swims, and he's still stuck with noticeable biceps and golden ringlets that give him no resemblance at all to Dustin Hoffman.

"I was always being the misunderstood young kid," says Katt, now 33, of a couple of early TV roles as psychopaths. "And then I was the Young Leading Man." It was at that point, while Katt was filming things like "First Love" and "Butch and Sundance: The Early Days" that someone--"I don't know who invented it, but I curse him"--dubbed him the new Robert Redford. "Until I landed on 'The Greatest American Hero' and became the goofy type."

But what he wants--what he hopes will follow his touring role in "The Pirates of Penzance," which opens tonight at Wolf Trap--is a classy feature film, a respectable Broadway show, something that matters. "You keep moving and working and hoping someone will see you and write you something that's important," says Katt. As he points out, "I still look relatively young."

He still looks like a Jan and Dean album cover (and he still surfs). Especially in the shorts and tank top and running shoes in which he's rehearsing with the "Pirates" chorus, sheathing an imaginary sword and dancing across the studio as the Pirate King until the choreographer announces, "It's come a long way, babies" and calls a break. Katt settles into a rehearsal room with a tuna sandwich.

He has developed a "much more positive outlook in my life," and in his interviews, aided by a recently hired PR firm coaching him to play up his amiability and serious intentions, he plays down his hunkier past. He is learning not to say nasty things about Spandex suits, to self-censor what sounds arrogant or misquotable, to publicly count his blessings.

"I was real angry for a long time, I suppose," Katt muses. "I suppose I was more innocent of how fickle the business can be. I'm not so innocent anymore."

After a splashy 1975 film debut as the sympathetic dreamboat in "Carrie," then three leads in noticed, if not applauded, movies, Katt's career suddenly stalled. Three projects in a row, one to be directed by Louis Malle, fell through. A record album called "Secret Smiles" defied Billboard predictions and flopped--inadequately marketed, sighs its writer and singer. Desperate not for money ("I was paid for three pictures I never made") but for work, he came to New York to star in the Phoenix Rep's production of the charged drama "Bonjour, La Bonjour," was seen and signed by the producer of ABC's "The Greatest American Hero" and broke "a three-year losing streak."

"I've worked straight through ever since. I'm on a roll. But after 'Carrie' I was on a roll, too, for three or four years," says Katt. "I hit bottom; now I've crawled back out."

Sadder but savvier, Katt no longer portrays himself as demeaned by the silly suit his "Hero" character Ralph Hinkley had to don from 1981 through early this year. "I got a lot of public attention I didn't get before" from the show, he acknowledges, "but it was a doubled-edged sword. There's always an inherent danger in getting so known for one part." He liked Ralph Hinkley, Katt insists, if he could only have freed him from that suit. "I always wanted to use the show as a social podium to speak on current events, make serious . . ." He stops to think--another tip from the PR people, no doubt.

"Comments?" offers the PR woman.

"Comments. We could have done things on ecology, stuff on Greenpeace, saving the whales." Norman Lear could get away with that, Katt points out. Katt couldn't--though he's quick to praise the show's producer and doesn't want to "sound like sour grapes."

"Besides, now I'm doing theater again and it makes me feel good," Katt adds, sounding very upbeat. "I'm working again as an actor. Even my wife says I'm different." Playing the Pirate King, following in the footsteps of actors such as Kevin Kline, puts him in line for serious Broadway work, he figures. He wouldn't have accepted the other "Pirates" lead, following the teen heartthrobs who've played Frederick. The king "is so flamboyant. He sparkles. Frederick is something I've done before, the young innocent. A Pippinish character," says Katt, who played Pippin in Bob Fosse's cable version of his Broadway hit.

During the Wolf Trap run, Katt's wife, Debbie, and 3-year-old son, Clayton, will fly in from California for visits to the Smithsonian and--a first for young Clayton--a chance to see Daddy on stage. "I can't wait till he comes," beams the Pirate King. And adds, in his positive persona, "I have the best wife and the best kid anyone could have. I make a good living. That beats 90 percent of the actors there are."

True, he doesn't have post-"Pirates" plans. This might unnerve even positive-thinking performers. Katt tells of meeting up with old actor chums in New York who ask what he's been up to, of telling them about a dozen glamorous projects from records to international tours to "Pirates," and then saying he's not sure what he'll do next. Oh, they say, that's too bad. "An actor's always looking for work; it's an odd reality," he muses.

But he's not biting his nails yet. His banked TV salary will give him the right to be selective for several years to come. His record label, MCA, has new management that might give him a better shot at a hit. There will be scripts to read. He has faith. "I just look forward to the future," Katt says sunnily. "I have a lot to give still inside of me, in music, in theater, every avenue the entertainment business offers me."

Now that he's shed his Robert Redford soubriquet, he's asked, how would he like to be known? "A multimedia star," Katt says, and then starts qualifying as he worries about the implications in print. "S---, I think I am. Certainly a multimedia talent. I don't know if I'm a star. Probably I'm not. I hope to be one. But," he decides, "I'd rather be thought of as someone who's respected."