She died shortly after 5 a.m. ET Sunday at Toronto's Bridgeport Health centre, said longtime friend and actor NickyGuadagni.
Public records say Griffiths was born in Montreal on Oct. 7, 1956, but her caretaker Layne Coleman told CBC she was was born on Oct. 7, 1953.
Griffiths co-wrote Maggie and Pierre with Paul Thompson and the play went on to tour Canada and earn headlines. She played both Pierre and Margaret Trudeau in scenes taking place from 1974 to 1980.
While preparing for the production, she enlisted the help of reporters to get into a Governor General's ball and managed to dance with Trudeau, who was between terms as prime minister after losing the spring of 1979 election.
"We seemed to dance for a very long time," she later wrote about the encounter, which allowed her to get an up-close impression of the man.
"He gave me his secretary's number, and I think he did this with ladies that he liked," she told an interviewer.
She later said in an interview for Theatre Museum Canada that she tried to play the role of Pierre respectfully, even at a time when he was reviled in parts of Western Canada.
Griffiths won five Dora Mavor Moore awards, including wins for Maggie and Pierre (1980) for both acting and writing, O.D. in Paradise (1983), Jessica (1986) and Alien Creature (2000).
She was also the recipient of a Gemini award, two Chalmers awards for Jessica and Alien Creature, and a Quizanne International Festival award for Jessica.
She was twice nominated for the Governor General's Award for The Darling Family and Alien Creature. Age of Arousal won her the Betty Mitchell Award for best new play in 2007.