The Canadian Broadcasting Corp. reported the cause of death as "complications" resulting from prostate cancer and Parkinson's disease. He had been in frail health since a bout of pneumonia in January.
"Pierre Trudeau, the embodiment of the dream of a just society, has left us," Prime Minister Jean Chretien said. "He is gone but his unfinished work remains â€“ our country, Canada."
Mr. Trudeau came to prominence at the height of social change in the 1960s, and his policies reflected the new ideas. As justice minister in 1967, he liberalized laws on abortion and homosexuality. He became Canada's 15th prime minister April 20, 1968.
A Montreal native, he made French an official language with English, promoted the metric system, led the fight against Quebec separatists, and in what was his most profound legacy, enshrined the Charter of Rights in a new Canadian Constitution in 1982.
Most controversially, during the "October Crisis" of 1970, as separatist terrorists exploded bombs and murdered officials in Quebec, Mr. Trudeau imposed the War Measures Act, ordering troops into the province and suspending civil liberties. The dramatic action won him the undying hatred of many French Quebecers, although repeated polls show that English Canadians consider him to be the greatest politician in the country's history.
His personality and influence were so strong, Mr. Trudeau was named Canada's newsmaker of the century in a 1999 Canadian Press-Broadcast News poll.
He married Margaret Sinclair, a "flower child" half his age, in 1971. They had three sons before their 1977 separation and eventual divorce. His youngest son died in an avalanche in 1998 at age 23; Mr. Trudeau's grief over the death was considered a factor in his hospitalization for pneumonia.
After his first marriage ended, he dated Barbra Streisand and actress Margot Kidder. At age 71, he fathered a daughter with his last wife, Deborah Coyne. That marriage also ended in divorce.
When Mr. Trudeau resigned as prime minister in 1984, these were his typically enigmatic farewell words: "It seemed like a good day to have a last day. ... I went out to see if there were any signs of my destiny in the sky. But there weren't; there was nothing but snowflakes."