(AP) -- Robin Williams, the Academy Award winner and comic supernova whose explosions of pop culture riffs and impressions dazzled audiences for decades and made him a gleamy-eyed laureate for the Information Age, died Monday in an apparent suicide. He was 63.

Williams was pronounced dead at his home in California on Monday, according to the sheriff's office in Marin County, north of San Francisco. The sheriff's office said a preliminary investigation shows the cause of death to be a suicide due to asphyxia.

From his breakthrough in the late 1970s as the alien in the hit TV show "Mork and Mindy," through his standup act and such films as "Good Morning, Vietnam," the short, barrel-chested Williams ranted and shouted as if just sprung from solitary confinement. Loud, fast, manic, he parodied everyone from John Wayne to Keith Richards, impersonating a Russian immigrant as easily as a pack of Nazi attack dogs.

He was a riot in drag in "Mrs. Doubtfire," or as a cartoon genie in "Aladdin." He won his Academy Award in a rare, but equally intense dramatic role, as a teacher in the 1997 film "Good Will Hunting."

He was no less on fire in interviews. During a 1989 chat with The Associated Press, he could barely stay seated in his hotel room, or even mention the film he was supposed to promote, as he free-associated about comedy and the cosmos.

"There's an Ice Age coming," he said. "But the good news is there'll be daiquiris for everyone and the Ice Capades will be everywhere. The lobster will keep for at least 100 years, that's the good news. The Swanson dinners will last a whole millennium. The bad news is the house will basically be in Arkansas."

Like so many funnymen, he had serious ambitions, winning his Oscar for his portrayal of an empathetic therapist in "Good Will Hunting." He also played for tears in "Awakenings," ''Dead Poets Society" and "What Dreams May Come," something that led New York Times critic Stephen Holden to once say he dreaded seeing the actor's "Humpty Dumpty grin and crinkly moist eyes."

Williams also won three Golden Globes, for "Good Morning, Vietnam," ''Mrs. Doubtfire" and "The Fisher King."

His other film credits included Robert Altman's "Popeye" (a box office bomb), Paul Mazursky's "Moscow on the Hudson," Steven Spielberg's "Hook" and Woody Allen's "Deconstructing Harry." On stage, Williams joined fellow comedian Steve Martin in a 1988 Broadway revival of "Waiting for Godot."