The actress, whose film and television credits span seven decades, was perhaps best known for her roles in films such as Planes, Trains and Automobiles and It Runs in the Family.
She was also known for playing Martha Evans in the NBC daytime soap opera Days of our Lives. Martha was the mother of twin daughters, Marlena (Deidre Hall) and Samantha (Andrea Hall). Douglas recurred on the show from November 1977 to February 1979. She appeared again in May 1982 when it looked like Marlena had been murdered by the Salem Strangler, although it turned out it was Sam who was killed.
Douglas' numerous other television credits included CBS daytime drama Love Is a Many Splendored Thing (as Lily Chernak Donnelly), and primetime series such as Dynasty (as Mother Blaisdel), The Paper Chase (as Professor Tyler), Knots Landing (as Dr. Charlotte Kramer), Dallas (as Dr. Suzanne Lacey) and The Cowboys (as Annie Anderson).
Douglas was married to fellow actor Kirk Douglas for eight years before their divorce in 1951. Together, the pair had two sons, Michael and Joel. In 1956, Diana Douglas married actor Bill Darrid, whom she remained with until his death in 1992. She married Donald Webster, a former treasury official in the Nixon administration, in 2002.