Born Charlotte Rae Lubotsky on April 22, 1926, in Milwaukee, Wisconsin, Rae attended Northwestern University, where she met many future stars, including Agnes Nixon, Charlton Heston, Paul Lynde, and Cloris Leachman, who would become a good friend.
Rae had revealed in 2017 that she had bone cancer but planned to fight it, telling People, "I've had a great life, but I have so many wonderful things happening".
Charlotte got her start in show biz through radio and theater, and broke into television acting on vehicle 53, Where Are You?
For almost a decade, she was the wise housemother of four girls at a boarding school, and to millions more watching their televisions, on the hit series, The Facts of Life.
"I grew up watching Charlotte Rae teach us the facts of life", wrote one Twitter user.
Rae also wrote about the grief of losing her son Andy, who had autism and epilepsy and died of a heart attack in his mid-40s. "I'm feeing so terrific and so glad to be above ground". I've had a wonderful one already...
Her publicist confirmed the actress' death to CBS2/KCAL9.
She also starred in several Broadway musicals in the 50s and 60s and received two Tony nominations, first in 1966 as best actress in Pickwick and again in 1969 for best actress in Morning, Noon and Night.
"Mindy Cohn, who played Natalie Green on Facts of Life, said: "[Rae] was my champion, a teacher, a proud example of the tenacity and perseverance needed to live as a creative, along with your talent and gifts...
"I wanted to be a serious actress and do all the classics", Rae told the Sun-Times in 1989.
At the time of that interview, Rae was acting at Chicago's Briar Street Theatre in the role of Daisy Werthan, the irascible heroine of "Driving Miss Daisy".
The Facts of Life star Kim Field tweeted: "You already know my heart is heavy yet, sorry, no words at the moment just love and tears and yeah, smiles".
Charlotte initially got her break as the kooky housekeeper Edna Garrett on Diff'rent Strokes.
She had two sons, Larry and Andrew, with her ex-husband, John Strauss, who she divorced in 1976 after he came out as bi-sexual.