By tradition, Drama is represented by two masks: the happy face of the comic muse Thalia and her sad counterpart, the tragic muse Melpomene.

If Drama were Robin Williams, you'd need a million more.

He was a mask of howling laughter, a mask of wide-eyed innocence. A sneer. A frown. Even, at times, a blank.

If it seemed like we knew what went on behind the many masks, it was because Williams' quicksilver mind and boundless talent possessed enough energy to blow them right off his face. He WAS Mork. He WAS Adrian Cronauer of "Good Morning, Vietnam." He WAS Patch Adams, and "Aladdin's" genie, and Mrs. Doubtfire.

But he was also the restrained Garp in "The World According to Garp," and the creepy Seymour Parrish in "One Hour Photo," and the firm but compassionate Sean Maguire in "Good Will Hunting," the performance that won him an Oscar.

It was that side of Williams - something raw and vulnerable, not something manic and boisterous - that made you wonder: who was he when he took off the mask?

On Monday, Williams was found dead in his home in Tiburon, California. He was 63. Coroner investigators suspect "the death to be a suicide due to asphyxia," according to a statement from the Marin County, California, Sheriff's Office.

It's a cliché, of course, the clown who laughs on the outside while crying - or dying - on the inside. It's Pavarotti's Pagliacci and Charlie Chaplin's Little Tramp; Willy Wonka and Laurence Olivier's Archie Rice.

Show business history is filled with stories of comic kings who fought against depression and substance abuse, not always successfully. Jonathan Winters, Williams' hero, was institutionalized for a time. The effortless Dick Van Dyke once said he was "mostly drunk for 15 years." John Belushi and Chris Farley died of overdoses.

Mitch Hedberg, Freddie Prinze, Richard Jeni - all funny men, all gone before their time.

There's no question that comedy can be a form of escape - and recognition. Richard Pryor, one of the most brilliant comedians who ever strode on stage, was raised in a brothel, married multiple times, struggled with demons both societal and personal. He was ruthless - especially on himself.

Yet he was scathingly, mercilessly funny. It was comedy that drew blood, comedy as catharsis.

Chris Farley, on the other hand, grew up in a close-knit, comfortable clan - but also sometimes seemed to be running from something. His immersion in Matt Foley, the divorced motivational speaker who lived in a "van down by the river," was both hilarious and a little scary.

"We lose at least one great comic to suicide or ODs every year," tweeted comedian Michael Ian Black on Monday. "Our jobs are to communicate, but we seem to not know how to ask for help."

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