Thelma Ritter appeared in high school plays and was trained at the American Academy of Dramatic Arts. In the 1940s she worked in radio. Her movie career was started with a bit part in the 1946 Miracle on 34th Street. In the movie she played a weary Xmas shopper. Her performance in the short scene was noticed by Darryl F. Zanuck who insisted her role be expanded. During the period 1951 to 1963 Ms. Ritter was nominated for 6 Academy Awards. She is one of the most nominated actors who never won the statue. Shortly after a 1968 performance on The Jerry Lewis Show, Ms. Ritter suffered a heart attack which proved fatal.
Won Broadway's 1958 Tony Award as Best Actress (Musical) for "New Girl in Town" in a tie with her co-star, Gwen Verdon . Mother of actress Monica Moran, they appeared together in a 1966 road show production of "Bye Bye Birdie" that also starred Tab Hunter.