'Happy Days' Cast Reveals How Robin Williams Got Cast as a "Martian" in Show's "Worst Script"

Three of the original Happy Days castmembers recently reunited to explain just how Robin Williams got cast as an alien on the comedy series.

"Mork & Mindy was like the worst script in the history of Happy Days. … It was unreadable, it was so bad," said Anson Williams, who played Potsie. He revealed that series creator Garry Marshall had gone to see Star Wars with his son, who asked his father if the show "could do a Martian episode."

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Anson Williams, along with Marion Ross (Mrs. Cunningham) and Don Most (Ralph Malph) recently appeared on Hallmark Channel's daytime series Home & Family to reminisce about the episode.

"So they hire some guy for Mork — bad actor, bad part," Anson Williams said of the first actor (not Robin Williams) hired to play the role.

"It wasn't his fault," Most chimed in.

Replied Williams: "You're always so nice. He was horrible!"

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So when that actor quit, Marshall asked for suggestions on who could replace him, asking: "Does anyone know a funny Martian?"

Watch the video above to hear the rest of the story — and the nice gesture Williams later did for the cast.

Home & Family,hosted by Mark Steines and Cristina Ferrare, airs 10 a.m.-noon weekdays on Hallmark Channel.