There are some things that everyone knows about Happy Days. That catchy "Sunday, Monday…" theme song still sock-hops its way around your brain. Fonzie is about as iconic as Mickey Mouse.

But nearly everything you know about Happy Days almost went another way. What is the theme song had remained "Rock Around the Clock?" What if the producers had stuck with one of the original working titles for the show — Cool or New Family in Town? What if Harold Gould had been asked back to play the father instead of Tom Bosley after the first pilot episode? What if Grease and American Graffiti had flopped? What if "the Fonz" had kept his original name in the script, "the Mash?"

Speaking of the Fonz — what if a different actor had landed the part? What if the Fonz was a Monkee?

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Before we get to that, let's look at how the character of the Fonz came to be. Happy Days began as a failure. In the original pilot, dubbed New Family in Town, the story centered around the Cunningham family, primarily teenager Richie, played by Ron Howard. His pal Potsie was there, plus his brother Chuck and sister Joanie. Of course, Mr. and Mrs. Cunningham played a part. But that was it for the core cast.

The network passed on the series, tossing it into an episode of Love, American Style, an anthology series that often served as a dumping ground for failed pilots. The suits felt that hip audiences of the Seventies would not care about the Fifties. This was in early 1972. 

But two pop culture phenomena happened around that same time. First, a quirky retro musical called Grease made the move from Chicago to Off-Broadway, where it quickly became a hit. A year later, American Graffiti, starring none other than Ron Howard, raked in piles of cash at movie theaters, stoking the flames of Fifties nostalgia. 

Suddenly, networks wanted a 1950s TV show.

New Family in Town was revived. Ron Howard, Marion Ross and Anson Williams returned, but the other roles were recast. 

In addition, Michael Eisner, then an exec at Paramount, wanted a fresh character. "We don't have a Paul Le Mat character," he told the creative team. In American Graffiti, Le Mat portrayed John Milner, the tough drag-racer who wore a white T-shirt and often kept a cigarette dangling from his lips. He was the James Dean, the greaser. 

"We need a gang, we need a bad guy," Garry Marshall later recalled Eisner saying in an interview with Archive of American Television. Marshall's mind immediately went to Gary Cooper and toughs from his own youth. He pictured the character — originally called "the Mash" until M*A*S*H was a smash — as a silent presence, standing as an imposing figure behind sunglasses. "A guy who didn't talk… who would point, do gestures," Marshall explained.

But who would play the leather-clad cool kid? That brings us back to the Monkees.

In a 2014 episode of Oprah: Where Are They Now?, Monkees member Micky Dolenz revealed, I was up for one show and I almost got it and it was Happy Days." Dolenz and the eventual Fonzie, Henry Winkler, even bumped into each other at the casting. Dolenz recalls Winkler admitting he would never beat out a Monkee for the role.

Winkler would have been right if not for height. 

Dolenz measures in at 6' 0". Winkler stands at 5' 6". Due to the height of the rest of the cast, producers favored Winkler, who would more easily fit in the frame with his castmates.

Likewise, the 6' 1" Michael Dolenz, who had played the "quiet Monkee," was passed over for the Fonzie gig. They were just too tall.

Thanks to a measuring tape, we missed out on "Aaaay, aaaay, we're the Fonzies…"