Robin Williams exploded into fame as that manic alien Mork from Ork, in the hit TV show Mork & Mindy in 1979.
It all began at Paramount Studios in Los Angeles.
Flowers adorn Williams' star on the Hollywood Walk of Fame.
In Boulder, Colorado, fans placed flowers and a sign at the Mork & Mindy house. In Boston, they left loving messages at the bench where he consoled young Matt Damon in Good Will Hunting.
At Caroline's Comedy Club in Midtown Manhattan, people are leaving photos and flowers remembering Robin Williams, who used to perform standup at this very club.
Williams' comedic genius served him well in his movie career.
What was the real Robin Williams like? Film critic Leonard Maltin knew him well.
He told INSIDE EDITION, "That first time I met him he was 'on.' From the moment he walked into the interview room. He knew when to cut the clowning and be serious in talking about the subject matter of the film."
Joan Rivers was his good friend. She told INSIDE EDITION, "What a waste. How sad. Truly, he was at the top of his game, he had the respect, he had the acknowledgement of everybody. What a tragedy that he couldn't live and enjoy it."
Hear More From Rivers
He was always "on" when we interviewed him. Williams won a Best Supporting Actor Oscar in 1998 for Good Will Hunting.
But there was plenty of turmoil in Williams' life. He was married three times. His second wife, Marsha Garces, had worked as a nanny for his first-born son.
Williams waged a lifelong battle against drug and alcohol addiction. He joked about it on The Daily Show last year, saying, "I was on everything but skates! Yes, I went to rehab in the wine country, just to keep my options open!"
On a serious note, he discussed the rehabilitation process with Larry King in 2007.
"People start the process of just saying no, and being among others, and learning that you're not alone and working on giving up," said Williams.
King asked, "Do you lose your sense of humor?"
"No. You find it," replied Williams.
But in recent years, there was less for Williams to laugh about. He suffered from depression, and he underwent open heart surgery in 2009, a potentially lethal combination.
Psychotherapist Dr. Robi Ludwig commented, "Any time you have a major medical issue on top of a major emotional issue, you combine that and who knows what impact that has on someone who's fragile emotionally."
His TV show The Crazy Ones didn't score with viewers. It was cancelled earlier this year after one season though he did get to share a tender reunion with Pam Dawber, his co-star from Mork & Mindy.
Dawber is heartbroken by the death of her old friend at age 63, saying, "I am completely and totally devastated. What more can be said?"
Williams had been preparing to star in a sequel to Mrs. Doubtfire, but apparently, nobody else can fill those shoes. The headline today in Variety says, "Mrs. Doubtfire sequel in doubt after Robin Williams' death."
But you haven't seen the last of Robin Williams. He'll be appearing in several yet-to-be released films, including Night at the Museum, Secret of the Tomb in December.
"Theodore Roosevelt, president of the United States!" says Williams in a clip from the film.