Happy Days: Then, Now, And Fun Facts
A Monkee Was The First Choice For The Fonz

It’s hard to imagine Henry Winkler’s role being filled by anyone else, but it was almost a reality. Monkees drummer Micky Dolenz read for the role but was ultimately turned down. It turns out that Winkler’s shorter stature made him a better pick for playing Arthur Fonzarelli.
Henry Winkler Couldn’t Read His Casting Script

Henry Winkler is dyslexic and when it came time to read six lines for his audition, he wasn’t prepared for the reading. Instead, he decided to make up his own words. He managed to convince the show’s casting directors that he was giving them a real feel for the character. His plan obviously worked and he played The Fonz for 11 very successful seasons.