He also made his mark as a stand-up comedian and a television star. He landed on the scene in ABC's "Mork and Mindy," which aired from 1978 to 1982. He became a comedic icon with signature improvisations and rapid switching between different characters.
"Williams was really the comic ... who took us out of the Nixon era. The guy came out and he was this bundle of energy with enormous intelligence," said MovieCityNews.com Editor David Poland.
"Robin Williams in addition to the sitcoms, in addition to the iconic comedies, in addition to dramas like 'One Hour Photo,' he was one of the top stand-up comics. He'd be on the 'Mount Rushmore' of stand-up comics with Richard Pryor and George Carlin," Roeper agreed.
Most recently, Williams had starred in "The Crazy Ones" on CBS, which was canceled after one season.
The apparent suicide of Williams on Monday at age 63 has been met with an outpouring of grief around the world from entertainment industry giants, like Disney CEO Bob Iger and filmmaker J.J. Abrams, to President Barack Obama to Defense Secretary Chuck Hagel, who praised him for his work entertaining the troops.