On the basis of his early career as an alien on the TV series "Mork and Mindy," no one would ever have accused Robin Williams of being subtle. His genius wasn't about that: It was about improvisation inspired by radio signals coming from who knows where, about jazzy free association and jittery synapses. What made Mork think eggs could fly? And yet when he tried to release them from the tyranny of gravity ("Fly, be free!"), flinging them into the air only to have them land with a soft thwack, it seemed like nothing so much as a stroke of loopy brilliance.

If Mork's shenanigans were inspired, they were also the sort of thing that could become wearisome in large doses -- which is why it was a good thing that Williams tried hard to fashion himself into a real actor early in his career, particularly in movies like Paul Mazursky's wonderful 1984 "Moscow on the Hudson." Between his geyser-force comic riffing and his willingness to dig into a dramatic role, Williams seemed to possess almost unfathomable potential.

That is, until he started going to such great lengths to warm hearts everywhere, leaving a sorry trail of them, charred and numb.

What happened to Robin Williams?

The short answer, and the only really plausible one, is that he's succumbed completely to the yearning that most entertainers feel at least to some degree. As critic Robert Warshow said of Charlie Chaplin, he makes one insistent demand: "Love me." Williams has practically admitted as much himself. In a recent unauthorized biography by Andy Dougan, pieced together from interviews Williams has given over the years, the actor is quoted as saying, "I'm no great shakes. It's the 'love me' syndrome coupled with the 'fuck you' syndrome. Like the great joke about the woman who comes up to the comic after the show and says, 'God, I really love what you do. I want to fuck your brains out!' And the comic says, 'Did you see the first show or the second show?'"

The quote is so frank, so blatantly self-confessional, that it's almost too easy. But it's also funny and acidic, in the manner of the old Robin Williams, and it shows more self-awareness than we'd believe possible, considering the gooey stickiness of Williams' work of the past few years. "Love me" is a grating, stultifying demand, the kind that can lead you to become disillusioned with even a highly gifted performer. But the old Robin Williams -- particularly the coked-up stand-up comic of the '80s, so charged up that he could leave audiences feeling dizzy -- didn't seem to be begging for our love so much as demanding (and commanding) our attention. The Williams of the old days forged a bond with his audience, and it wasn't necessarily a comfortable one -- but its prickliness was part of what made him so vital.

Now, with movies like "Mrs. Doubtfire" (1993), "Patch Adams" (1998) and "What Dreams May Come" (1998) -- the first two huge box-office hits -- Williams seems to have become most interested in smothering us in a massive warm fuzzy. And the heartwarming Holocaust drama he's due to release later this month, "Jakob the Liar" -- which is based on the novel by Jurek Becker, made into a German-language film in 1974 -- suggests nothing so much as a desperate attempt to outgrin the insufferable Roberto Benigni (although Williams filmed the role before he did "Patch Adams").

The state of Williams' career may be the inevitable result of an actor's becoming successful enough to develop his own projects (he's pointed with pride to the fact that the dreadful "Mrs. Doubtfire" was "found" by his wife and colleague, Marcia Garces Williams). Who's to say that some actors aren't better off when they're chosen or pursued by a particular director, instead of having the freedom, the money and the clout to spearhead any project they choose and make themselves the centerpiece of it? Williams has complete control of his own destiny at this point. "Patch Adams" (again, executive-produced by Marcia Garces Williams) grossed some $135 million in theaters, proving that large audiences are following. Why shouldn't Williams continue merrily on his way, making big bucks as he spreads his special brand of love and happiness across the land?

He could, and he probably will. It's wonderful that he's so successful; it's tragic that he's such a disappointment.

Williams is one of a rare breed, both a brilliant, quicksilver comic and a wonderful actor. When he reins himself in, his sense of humor informs his dramatic performances without overwhelming them. But the roles he's best known for (particularly the Oscar-winning one in "Good Will Hunting," merely a crustier reworking of the ultra-admirable role-model professor he played in "Dead Poets Society") aren't necessarily his most astonishing. His work in movies like "The Best of Times" (1986) and "Cadillac Man" (1990) has been all but overlooked. And the two pictures in which he really shines, without turning on that phony 100-watt beaming -- "Moscow on the Hudson" and the 1991 "The Fisher King" -- are written off by many viewers simply because they got mixed reviews or did poorly at the box office.

"Moscow on the Hudson" was released in 1984, after Williams had had just a handful of starring roles (including Robert Altman's disastrous 1980 "Popeye," a movie that squandered the talents of everyone involved, including Williams, Altman and Shelley Duvall). As Vladimir, a Russian musician who decides to defect to the United States during a brief visit (in the middle of Bloomingdale's, no less), Williams seemed to tap deep reserves of feeling, rather than just glib approximations of it: It's a wary, cautious performance, but also, paradoxically, a jubilant one.

Part of what makes it work is that Williams relies so little on shtick. His thick Russian accent is the only element reminiscent of a comedy bit; otherwise, he sinks himself physically and emotionally into the character, with very little gimmickry. His confusion and vulnerability, his bewilderment at finding himself in the role of stranger in a new land, are mostly telegraphed through the way his eyes soften, or by the bemused glint that flickers there now and then. His body language alone is something to behold: As befuddling as the whole American experience is to Vladimir, he seems to be fending it off with every muscle. He swaggers, walks with a little bounce in his step. And with his stubby, vaguely simian build, Williams exudes an unquestionable sexual confidence with the object of his affection, Maria Conchita Alonso. Vladimir may be a stranger in this new country, but Williams shows how perfectly at home he is in his own skin.

Williams is terrific in almost every scene, but he has one moment that's worthy of Buster Keaton. He's just defected, barely, and as he watches the bus carry off his colleagues and compatriots, as well as his tenor sax (he's a circus musician who's come with his troupe to perform in New York), reporters cluster around him to ask him what he's feeling. He knows he'll never see his friends -- or his horn -- again. With a dazed grin frozen on his face, and his eyes closed up almost tight enough to hide the sorrow there, he says in his rough English, "I'm saying good-bye to my saxophone. I'm very happy to be here."

"Moscow on the Hudson" got some decent reviews, but audiences didn't take to it. People decried it as Reagan propaganda, a way of making life in the Soviet Union look far worse than it actually was. (In retrospect especially, those criticisms seem ludicrous.) Maybe that's why, in any serious discussion of Williams as an actor, "Moscow on the Hudson" tends to fall off people's radar, giving way to higher-profile, super-uplifting (as well as deeply conventional and deadly dull) performances like the ones Williams gave in "Dead Poets Society" and "Good Will Hunting." The 1987 "Good Morning Vietnam" is often cited as the movie that finally put Williams' skills to best use -- but it isn't so much acting as an excuse for Williams to do his stand-up routine.

Williams is always at his best when he doesn't use humor to whack us over the head. In Terry Gilliam's flawed masterpiece "The Fisher King" -- if a movie could have a heart of gold, this one surely would -- Williams plays Parry, a former professor who comes undone after witnessing his wife's murder; he ends up homeless and mentally unstable. Williams is funny in all the obvious Williams ways: leading a group of mental-ward patients in an enthusiastic reading of "How About You?"; or frolicking naked in Central Park (his hairy torso so repellently compelling you can barely take your eyes off it), exhorting his pal, played by Jeff Bridges, to do the same and "Free up the little guy! Let him flap in the breeze!" He's just restrained enough to make these bits work; he seems to know intuitively that he doesn't have to push hard. And in his moments with Amanda Plummer (as the shy, gawky girl he's fallen in love with from afar), he radiates a quiet tenderness that's bound tight with his fragility. He's blissfully in love with her, and it shows, but when he confesses how he feels for her, you also understand how dangerous the admission is for him. The emotional turbulence you see just behind the soft light in Parry's eyes is enough to send him right off the rails, and for a time, it does.

For whatever reason, though, in the years since "The Fisher King," Williams has taken it as his personal mission to make people "happy" in the most pedestrian and clumsy ways imaginable -- from playing a man-child in "Jack" (1996) to his role in a forthcoming project called "Taxi Dog," about a New York cabbie who befriends a homeless dog named Maxi. Williams' problems with drugs and philandering during the '80s were well-covered in the press; perhaps he's trying to atone for his sins by making mawkish family pictures with no sense of shame. Now he's a one-man Times Square, squeaky clean and safe even for tourists.

"Mrs. Doubtfire" seemed to usher in a new era for Williams. The picture was a tremendous hit, a gaily packaged laugh riot with a nice little moral about the importance of keeping families together, something you could take the kids to on a Saturday afternoon. Kids supposedly cotton to the character of Mrs. Doubtfire, but she scares the hell out of me: Her face is rendered almost immobile by strata of latex and pancake makeup, and her nasolabial fold is simply nonexistent -- creepy. Her relentlessly twinkly blue eyes are the only place I can see Williams in her. It's as if he's been swallowed by a pod lady. This is fun for kids?

"Patch Adams," about a doctor who believes in treating his patients with humor as well as medicine (and based on a true story), is marginally more enjoyable, but again Williams kicks his mugging and sermonizing into high gear. I disliked "Patch Adams," but when Williams was allowed to be Williams-trapped-in-the-body-of-Patch-Adams, I laughed. As when, trying to woo a fellow medical student, he half hides himself behind a skeleton and waves its arm enthusiastically, calling out, "Donner, party of 50!" (Similarly, in "Mrs. Doubtfire" he briefly tried on a number of disguises, from a yenta in a babushka to Barbra Streisand, and these miniature cameos were delightful.) Williams is funniest when he's riffing, but that's not exactly acting. In fact, it's not the "new" Williams himself that I dislike -- I still enjoy his zaniness, his spontaneous bursts of inventiveness. It's Williams' trying to soothe the psyches of the people -- smoothing out all his rough edges until there's nothing left but slick surface -- that's so difficult to deal with.

Williams has a speech in "Patch Adams" that's telling, revealing something of the questionable motives of even seemingly generous performers. Patch explains to the woman he's wooing why he decided to become a doctor: "I tried to kill myself. The mental ward was the best thing that ever happened to me ... It helped me realize that by helping [the other patients] I could forget about my own problems. And I did ... I really helped some of them. It was an incredible feeling."

Purely intentionally, of course, Williams has just drawn what seems like a neat little parallel between people who work in the medical and entertainment fields. Sure, there's generosity involved both in making people laugh and in saving their lives. But beyond that, the comparison is shaky. Doctors, like entertainers, may now and then get that "incredible feeling" from helping people, and they may feel deeply satisfied by their work; but ultimately they have to be less interested in making themselves feel good, and more motivated by a sense of duty to their patients.

Williams' pronouncement, made through the ventriloquist's dummy of the excessively smiley Patch Adams, is less about helping people than it is about going after his own happy glow. There's a selfish high that comes with entertaining people, and it's not an entirely bad kind of selfishness -- a performer can't give endessly without getting something in return.

But pleasing an audience is different from feeding on its approval. Williams used to know how to move an audience in the subtlest ways, with a look or a gesture or a line reading. Giving that kind of pleasure is a calling of sorts; it's not the sort of thing every performer can do, and Williams -- one of the lucky few who had the knack -- seems to have foregone it completely. Mrs. Doubtfire may have been scary. But Dr. Williams, with his magic vitamin for feeling good, is downright depressing.