It pays to heed the advice of eight-year-olds. Even if you are a successful television creator. In 1977, Garry Marshall was soaring off the triumph of his two babies, Happy Days and Laverne & Shirley. The retro sitcom and its spin-off sat atop the Nielsen Ratings, No. 1 and No. 2. Marshall witnessed the shows' winning effect on his two daughters. Lori and Kathleen Marshall adored the Fonz. 

"The girls were always clamoring to bring their friends to the live [Happy Days] filming Friday night on the Paramount lot," Marshall wrote in his memoir, My Happy Days in Hollywood.

His boy, on the other hand, wasn't too impressed. Scott Marshall only cared about Star Wars.

"I found it unsettling that Scott was a fan of George Lucas but not a fan of mine," Marshall admitted. "I had to find out why."

"There are no space aliens on Happy Days," the kid complained. The elder Marshall pointed out the improbability of E.T.s turning up in 1950s Milwaukee. This was a sitcom about high schoolers, largely set in a hamburger joint. How could aliens work into the plot?

Scott had a workaround: "Fonzie could have a dream." Of course! The tried-and-true dream sequence! The Dick Van Dyke Show used the technique all the time! Danny Thomas had played an alien from outer space who met Rob Petrie.

"We'd created Fonzie as a gangster with a heart of gold, and Mork was crafted as an alien with a heart of gold," Marshall explained. 

Thus, Mork from Ork was born.

But Robin Williams was not the first actor chosen for the role. Marshall was set on booking John Byner to play Mork. Marshall loved the "wild look in his eyes and [his] off-beat wit." 

Sony Pictures TelevisionJohn Byner on 'Soap'

Byner was best known as an impressionist. On The Ed Sullivan Show, the comedian mimicked the host himself. He could also effortlessly slip into the skin of John Wayne and Johnny Mathis. On an episode of Get Smart, "The Hot Line," Byner had even perfectly aped President LBJ. 

In 1972, CBS gave Byner his own showcase, The John Byner Comedy Hour. It was on this short-lived sketch series that Bob Einstein first introduced his beloved, bumbling stuntman character Super Dave Osborne.

Marshall and the network made a tentative deal for Byner to play Mork. Then, days before the episode, "My Favorite Orkan," was set to film, Byner quit the role. "Byner decided he didn't want to play an alien on a television series," Marshall wrote.

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Did you know?

Richard Lewis almost played Mork on Happy Days

So it immediately went to Robin Williams, you ask? Not so easily. The talent pros at the William Morris Agency pushed comedians Richard Lewis and Jeff Altman on Marshall. Marshall did not think they were "quite right."

A talent agent reluctantly offered up a new signing, a comedian who's experience was largely on street corners.

"You want me to build a major network sitcom around a man who passed the hat for tips," Marshall scoffed.

"It was a VERY full hat," the agent quipped.

As we all known in hindsight, Williams aced his audition — and slew the studio audience at the taping of the "My Favorite Orkan." 

As Mork & Mindy was in its first hit season, Williams triumphantly returned to Happy Days for the episode titled, well, "Mork Returns." Just one year later, this "newcomer" was already a ratings booster. John Byner, meanwhile, was playing Cybill Shepherd's elevator operator in the made-for-TV movie A Guide for the Married Woman and Detective Donohue on Soap. He was right when he felt the role of Mork was silly. Turns out, silly sells.