3. Arthur "The Fonz" Fonzerelli (Happy Days)
Happy Days began as a simple wholesome family sitcom set to revolve around young Richie Cunningham and his best friend Potsie. Motorcycle riding tough guy The Fonz was only intended to be a background character who occasionally showed up to make the clean cut teens nervous. But the performance of actor Henry Winkler very quickly put the kibosh on that. Young female fans swooned over the dreamy bad boy, while young male fans thought he was badass and wanted to be him. It wasn't long before his signature hand motions and "Ayyyy" catchphrase were being echoed in every day life by viewers, and producers decided to upgrade his role to main character. Potsie was soon demoted to third wheel while Fonzie filled the best friend role, and entire episodes were built around the Foz. Network execs even wanted to change the show's title to "Fonzie's Happy Days", but Winkler himself protested the idea with the rest of the cast backing him up. Winkler became so synonymous with the Fonz that even to this day he reports meeting fans who ask him to do "the Fonzie Thing".