Aug. 13, 2014 at 8:43 AM ET
Robin Williams was a virtual unknown when he first appeared alongside Henry Winkler on "Happy Days" in 1978 as alien Mork from Ork. But the moment Winkler met Williams, he knew the man in the red jumpsuit was no ordinary guest star.
"Unless you were in the ground, you knew that you were in the presence of greatness," Winkler, who starred as The Fonz on the series, told TODAY Wednesday. "That's not talking because now we're making a tribute; that is the honest truth. This man was from another plane. His imagination flew out of him, out of every pore like a torrent."
The show, Winkler remembered, had a hard time casting the role of an alien sent from a distant world to study Earthlings. Then a "young, very quiet, very delicate man" — Williams — appeared on set, and everything changed. Said Winkler, "All of a sudden all you see are sparks."
Winkler recalled a behind-the-scenes moment when his Fonz character asked Mork, "Hey, you want to rumble?" That was all it took for Williams to go off on one of the side-splitting stream-of-consciousness riffs for which he would become famous. Said Winkler, "I'm telling you that I could not look him directly in the face for the next two-and-a-half days."
That "Happy Days" episode was the only launching pad Williams needed. By the time he returned for a second appearance in 1979, he was already a star on his own series, "Mork & Mindy."
Williams' death was "so tragic because he was so loved," Winkler told TODAY. "It's just amazing how he touched the world."
Want to see Williams' debut as Mork in the classic "Happy Days" episode, "My Favorite Orkan"? The Hub Network will play it twice in a row starting at 9 p.m. ET on Aug. 15.