15. "Happy Days" (ABC) — 30.5 million viewers

This nostalgic look at life in the 1950s premiered in 1974 and the series finale aired on September 24, 1984. It revolved around the wedding of youngest daughter Joanie (Erin Moran) and Chachi's (Scott Baio) wedding. The Fonz (Henry Winkler) beats regulations limiting a single person from adopting and takes on the boy who he was fostering.