Simmons returned to the big screen in 1963 in "All the Way Home," giving an "award-caliber performance" as a recently widowed mother, according to "Leonard Maltin's Movie Guide."
But she found good roles harder to come by.
"Every actress has to face the facts there are younger, more beautiful girls right behind you," Simmons said in 1988 in the Toronto Star. "Once you've gone beyond the vanity of the business, you'll take on the tough roles."
Increasingly, she turned to television movies and miniseries.
In the 1980s, she appeared in the ABC historical drama "North and South" and its sequel; in a well-reviewed Disney Channel version of "Great Expectations" as the miserable recluse Miss Havisham; and as the mother, Fiona "Fee" Cleary, in the ABC miniseries “The Thorn Birds.”
"I didn't have a dominant personality. It helped me slip into character parts very easily," she told the Toronto Star in 1988. "I simply had to play the mother in 'The Thorn Birds.' I understood her pain. I badgered the producer until he gave in. He said it wasn't a star part. That's why I wanted it!"
Jean Merilyn Simmons was born Jan. 31, 1929, in London to Charles and Winifred Ada Simmons.
Her father competed as a British gymnast in the 1912 Olympics and later coached the sport. He died when she was 16.
Her mother once described Cricklewood, the north London area where Simmons grew up, as "a place where they make lovely parts for automobiles."
At 15, Simmons appeared in five British films, including a role as a precocious teenager in "Give Us the Moon." She also appeared in such major British productions as "Black Narcissus" (1947) and "The Blue Lagoon" (1949).
In 1956, she became a U.S. citizen and while married to Granger lived on an Arizona ranch.
For years, she lived in a Santa Monica home that she decorated in a style she once described as "early mishmash."
"It was extraordinary for a Cockney kid from Cricklewood to have this happen," she said in a 1989 Times interview as she expressed amazement over the life she had lived. "If I hadn't gone to that dancing school, I would have married and had children like my mum and had a normal life.
"My career has had a lot of ups and downs," she said, "but basically it has been wonderful."
She is survived by her two daughters, Tracy Granger and Kate Brooks.
Instead of flowers, the family suggests donations be made to the Lange Foundation, a pet rescue organization, at www.langefoundation.com.