Dinah Beth Manoff (born January 25, 1956) is an American stage, film, and television actress and television director. She is best known for her roles as Elaine Lefkowitz on Soap, Marty Maraschino in the film Grease, Libby Tucker in both the stage and film adaptations of I Ought to Be in Pictures, for which she won a Tony award, and Carol Weston on Empty Nest. She has starred in numerous television movies and guest-starred on various television programs. She mostly appeared on TV during the 1990s, but she has been seen in more recent theatrical films, such as The Amati Girls and Bart Got a Room, and a co-starring role on State of Grace.

Manoff is the daughter of actress Lee Grant and screenwriter Arnold Manoff. Since 1997, Manoff has been married to Arthur Mortell, and currently resides in Bainbridge Island, Washington. She previously had been married and resided in Los Angeles and New York City.