The Emmy Award-winning and Oscar-nominated actress died Sunday of bladder cancer, The Hollywood Reporter said Tuesday.
Brennan was perhaps best known for her Oscar-nominated performance as Army Capt. Doreen Lewis in the 1980 comedy "Private Benjamin" and a subsequent television series based on it, for which she won an Emmy in 1981.
Brennan was nominated for seven Emmys in all.
Brennan's other film credits include "The Sting," "Murder by Death," "Clue," "Daisy Miller," "At Long Last Love," "Texasville," "The Cheap Detective," "Scarecrow," "The New Adventures of Pippi Longstocking," "Stella," "Jeepers Creepers" and "Miss Congeniality 2: Armed and Fabulous."
On the small-screen, she was a regular on the sketch comedy series "Rowan & Martin's Laugh-In" and had a memorable guest appearance on the sitcom "All in the Family," the entertainment industry trade newspaper said.
Brennan was married to poet-photographer David Lampson from 1968 until they divorced in 1975.
She is survived by her sons Sam and Patrick, daughter-in-law Jessica, sister Kate and grandchildren Liam and Maggie, The Hollywood Reporter said.