Famous for her comedic portrayal of Selma Hacker on the popular NBC series Night Court, she is also notable for her recurring role on the ABC sitcom Too Close for Comfort. Also a television writer, she contributed to Your Show of Shows and Caesar's Hour, receiving an Emmy nomination for her work on the latter program.
After graduating from New York University, she wrote for The New Yorker and for radio programs such as The Adventures of Ozzie and Harriet and You Bet Your Life.
Over the course of her career, she acted in episodes of The Edge of Night, McMillan and Wife, and Archie Bunker's Place.
She spent her earliest days in Ontario, Canada, and the bulk of her childhood in New York City. She later relocated to Los Angeles, where she died of lung cancer in her early sixties.
In the early 1950s, Diamond wrote for the Tallulah Bankhead-hosted radio program The Big Show.