Williams -- the 62-year-old Oscar winner for "Good Will Hunting" and star of the new CBS ad-industry sendup "The Crazy Ones" (a sneak peek is above) -- became an overnight sensation as the manic but endearing Mork on the ABC sitcom, which was spun off from "Happy Days" and ran from 1978 to 1982.
For many boomers, Mork remains a fond relic from childhood. But a relic he shall have to remain, because Williams says he'll never go back to the character.
"It's too late for that," Williams wrote during an Ask Me Anything forum on Reddit Wednesday. "But [Mork] had a great run and I had a wonderful time doing it, and I recently re-watched the episode of Happy Days that launched the character as a one-off, and it was really funny."
In later episodes of "Mork," producers added legendary comic Jonathan Winters to the cast. Winters, who died last year, was a deep influence on Williams and he paid tribute to him at Sunday's Emmys telecast.
"He would perform for anybody," Williams wrote on Reddit. "There was no audience too small. I think I once saw him do a cat for a beagle."
What do you think of Williams and his work on "Mork"? Will you watch "The Crazy Ones"?