Sternhagen is a familiar face to TV viewers. She is probably best-known for her recurring role as the mother to mailman Cliff Clavin (John Ratzenberger) on the NBC comedy "Cheers". Sternhagen began appearing on the small screen in the 1950s and spent the better part of the late 60s and early 70s in a variety of roles on daytime soaps ("Love of Life", "The Doctors", "The Secret Storm" and "Another World"). In primetime, she has played regular supporting roles in everything from sitcoms ("Under One Roof") to drama ("Stephen King's Golden Years").

Sternhagen also has extensive stage credits in everything from classic plays to musical comedies. She has received two Tony Awards for Best Supporting Actress in a Play for Neil Simon's "The Good Doctor" (1974), based on Chekhov works to a revival of "The Heiress" (1995), based on the Henry James' novella. Sternhagen was married to actor Thomas A. Carlin from 1956 until his death in 1991.