Trevor won an Academy Award for her 1948 performance as a drunken, heart-broken former singer in Key Largo alongside Lauren Bacall, Humphrey Bogart and Edward G Robinson.
She was also in John Ford's 1939 classic Stagecoach, playing a frontier prostitute redeemed by John Wayne.
She died at a hospital near her home in Newport Beech, California. No cause of death was given.
A 'rotten' singer
In a career spanning more than 50 years, Trevor earned Oscar nominations for Dead End, a 1937 melodrama in which she played a good girl who grows up to be a prostitute, and for The High and the Mighty, a 1954 aeroplane disaster epic.
In one scene, he forces her to sing for a drink she badly wants. Trevor struggles through the song only to be refused the drink by Robinson "because you were rotten."
In the 1950s, she appeared in a number of television dramas and won an Emmy Award in 1956 for her performance in Dodsworth.
Her last feature film was Breaking Home Ties in 1987.
A theatre at the University of California is named in Trevor's honour.
A series of marriages
Trevor was born Claire Wemlinger in New York in 1910.
She married film producer Clark Andrews in 1938, but they divorced four years later.
Her second marriage to Cylos William Dunsmoore produced a son, Charles. But this too ended in divorce in 1947.
The next year, Trevor married Milton Bren, another film producer.
In 1978 Charles died in an airliner crash and her last husband, Milton, died from a brain tumour in 1979.
Trevor's funeral service will be held in private, and a memorial service is being planned.