“Chris was an extraordinary man who deeply loved and respected his profession with great old-fashioned manners, self-deprecating humour and the music of words," Pitt said. "He was a National Treasure who deeply relished his Canadian roots. Through his art and humanity, he touched all of our hearts and his legendary life will endure for all generations to come."
Plummer passed away peacefully at his home in Connecticut with his wife Elaine Taylor at his side, Deadline Hollywood said.
Plummer, an accomplished Shakespearean actor honoured for his varied stage, television and film work in a career that spanned more than six decades, was best known for his role in "The Sound Of Music," which at the time eclipsed "Gone With the Wind" (1939) as the top-earning movie ever.
Plummer flourished in a succession of meaty roles after age 70 - a time in life when most actors merely fade away. He claimed a long-awaited Academy Award at age 82 for his supporting performance in "Beginners" as an elderly man who comes out of the closet as gay after his wife's death.
"You're only two years older than me, darling," Plummer, who was born in 1929, purred to his golden statuette - first given for films made in 1927 and 1928 - at the February 2012 Oscars ceremony. "Where have you been all my life?"
Plummer became the oldest actor to win a competitive Academy Award - supplanting Jessica Tandy and George Burns, who both were 80 when they won theirs.
Plummer appeared in more than 100 films and also was nominated for an Oscar for his portrayal of Russian author Leo Tolstoy in 2009's "The Last Station." He won two Tony Awards for his Broadway work, two Emmy Awards for TV work and performed for some of the world's top theater companies.
But for many fans his career was defined by his performance as an stern widower in "The Sound Of Music" - a role he called "a cardboard figure, humorless and one-dimensional." In his 2008 autobiography "In Spite Of Myself," Plummer refers to the movie with the mischievous acronym "S&M."
It took him four decades to change his view of the film and embrace it as a "terrific movie" that made him proud.
Director Robert Wise's wholesome, sentimental film follows the singing von Trapp family and their 1938 escape from the Nazis. Plummer's character falls in love with Andrews, portraying a woman hired to care for his seven children. The movie won the Academy Award as best picture of 1965.
"Originally I had accepted Robert Wise's offer simply because I wanted to find out what it was like to be in a musical comedy," Plummer wrote in his book. "I had a secret plan to one day turn 'Cyrano de Bergerac' into a Broadway musical. 'S&M' would therefore be a perfect workout in preparation for such an event."
He said he had never sung before in my life - "not even in the shower" - before taking a role that included crooning the song "Edelweiss." He blamed his own "vulgar streak" for the desire to star in a big, splashy Hollywood extravaganza.
"And yes, all right, I'll admit it, I was also a pampered, arrogant, young bastard, spoiled by too many great theater roles," he wrote. "Ludicrous though it may seem, I still harbored the old-fashioned stage actor's snobbism toward moviemaking."
LATE-CAREER RENAISSANCE
Plummer's late-career renaissance began with director Michael Mann's "The Insider" (1999) in which he portrayed CBS News interviewer Mike Wallace, acting alongside Al Pacino and Russell Crowe.
That was followed by triumphs in director Ron Howard's Academy Award best picture winner "A Beautiful Mind" (2001), director Spike Lee's "Inside Man" (2006), "Up" and "The Imaginarium of Doctor Parnassus" (both 2009) and "Barrymore" and "The Girl with the Dragon Tattoo" (both 2011).
Plummer was born in Toronto on Dec. 13, 1929, into a privileged railroad family. He was the great-grandson of Sir John Abbott, the third prime minister of Canada.
Plummer confessed to a boozy lifestyle with plenty of affairs through the 1960s. He said his third wife, British actress Elaine Taylor, forced him after their 1970 marriage to stop the carousing that consumed some of his peers and friends, such as Richard Burton and Peter O'Toole.
"Yeah, I stopped," he told Britain's Telegraph newspaper in 2010. "Square son of a bitch that I was, coward that I was! No, Elaine did say, 'If you don't quit this stupid over-drinking I'm outta here.' And thank God. She did in a sense save my life."
Plummer's early films included 1965's "Inside Daisy Clover" with Natalie Wood and Robert Redford, released the same year as "The Sound Of Music," "The Fall of the Roman Empire" (1964) with Sophia Loren and Alec Guinness, and "Triple Cross" (1966).
Among his more colorful roles were as an eye-patch-wearing Klingon in "Star Trek VI: The Undiscovered Country" (1991) and as an urbane jewel thief in "The Return of the Pink Panther" (1975). He said he kicked himself for turning down the Gandalf role in the popular "The Lord of the Rings" trilogy.
One of his last major roles was as another patriarch, in the dark-comedy "Knives Out" in 2019.
His TV roles included the 1983 mini-series "The Thorn Birds."
Plummer lived with Elaine in Connecticut. He was the father of Tony Award-winning actress Amanda Plummer.
