9. Welcome Back, Kotter
When he wrote and recorded the theme to Welcome Back, Kotter in 1975, John Sebastian was definitely not a one hit wonder. In fact, "Welcome Back" was one of seven top-10 hits for the frontman of the Lovin' Spoonful. After this success, Sebastian admitted that he initially struggled to write lyrics rhyming with "Kotter" and eventually just gave up. The unexpected star of the program was not Kotter, portrayed by Gabe Kaplan, but a very young John Travolta, who occasionally broke into song.