Diane Ladd (born November 29, 1932 in Meridian, Mississippi) is an American television and film actress. She was born Rose Diane Lanier and raised Catholic. She is a distant relation of the late great playwright Tennessee Williams.

She had a supporting role in Roman Polański's 1974 film Chinatown, and was nominated for an Academy Award for Best Actress in a Supporting Role for her role as Flo in the film Alice Doesn't Live Here Anymore. That film inspired the TV series Alice in which Flo was portrayed by Polly Holliday. When Holliday left Alice, Ladd was cast in the show as Flo's replacement, waitress Isabelle "Belle" Dupree. Despite her success in the film version, Ladd's role in the television spinoff proved unpopular with viewers of the series and she appeared for only the 1980-1981 season. In 2004, Ladd played psychic Mrs. Druse in Stephen King's miniseries Kingdom Hospital. In April 2006, Diane Ladd released her first book entitled: A Mental, Physical, and Spiritual Discovery.