She was 80.
Her agent, Judy Page, told the Los Angeles Times that Simmons died Friday night at her home in Santa Monica. Simmons had lung cancer.
Simmons made her movie debut at age 14 in the 1944 British film Give Us the Moon.
She would go on to star opposite Kirk Douglas in Spartacus and Burt Lancaster in Elmer Gantry.She was best recognised for playing opposite Marlon Brando in Guys and Dolls.
Simmons won an Emmy for the 1983 TV miniseries The Thorn Birds and appeared on TV and on stage until the 1990s.
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