Lafleur had been diagnosed with lung cancer, but a cause of death has not been released, The Associated Press reported.
Tumors were found when he was undergoing emergency quadruple bypass surgery.
“We are deeply saddened to learn of the death of Guy Lafleur. All members of the Canadiens organization are devastated by his passing,” Canadiens President Geoff Molson said in a statement to the AP.
“Guy Lafleur had an exceptional career and always remained simple, accessible, and close to the Habs and hockey fans in Quebec, Canada and around the world. Throughout his career, he allowed us to experience great moments of collective pride. He was one of the greatest players in our organization while becoming an extraordinary ambassador for our sport.”
Lafleur was born on Sept. 20, 1951, in Thurso, Quebec.
He got his start playing peewee hockey in Canada. He played junior hockey for the Quebec Jr. Aces and Quebec Ramparts, leading the ramparts to the Memorial Cup title in 1971, CBC reported.
Nicknamed “The Flower,” Lafleur was drafted in 1971 as the No. 1 pick.
He had 518 goals and 728 assists when he played for the Canadiens and in 124 playoff appearances, the right wing had 133 points — 57 goals and 76 assists, the AP reported.
He had six consecutive seasons with at least 50 goals and 100 points, CBC reported.
Lafleur also brought the Canadiens four consecutive Stanely Cup titles from 1976 to 1979. He also won the Hart Trophy twice and the Conn Smythe Trophy for playoff MVP in 1977, CBC reported.
In 1981, he was almost killed in a car crash while driving home. A post smashed through the car’s windshield, missing his head by inches, CBC reported.
Lafleur retired shortly after the start of the 1984 season, but returned for the 1988-89 season, after being selected for the Hall of Fame in 1988, playing for the New York Rangers. The following two seasons he played for the Quebec Nordiques but then retired a second time after the end of the 1991 season, the AP reported.
Lafleur left behind his two sons, Mark and Martin, and Lise, his wife, CBC reported.
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Through the years Montreal Canadien Guy Lafleur kisses the Stanley Cup while Montreal captain Henri Richard holds the cup Thursday night, May 10, 1973 in Chicago. Montreal beat Chicago 6-4 and won the National Hockey League playoff. (AP Photo) (Anonymous/ASSOCIATED PRESS)
Through the years Guy Lafleur, of the Montreal Canadiens is pictured in 1974. (AP Photo) (AP)
Through the years Central Red Army forward Valeri Kharlamov (17) is taken out of the action by Montreal Canadians? forward Guy Lafleur (10) in third period action at the Montreal Forum in Canada on Wednesday, Dec. 31, 1975. The teams tied 3-3. (AP Photo) (Anonymous/ASSOCIATED PRESS)
Through the years Guy Lafleur, right, of Montreal Canadiens attempts to deflect stick of Phil Russell of Chicago Black Hawks from puck during NHL action at Chicago, Dec. 8, 1976. (AP Photo/Larry Stoddard) (Larry Stoddard/AP)
Through the years Montreal Canadiens' Guy Lafleur, center, is shown with team captain Serge Savard, left, and Yvan Cournoyer after winning the Conn Smythe Most Valuable Player trophy in the team's dressing room at Boston Garden in Boston, Ma., May 14, 1977. Montreal swept Boston in 4 games to win the Stanley Cup championship title. Cournoyer is on the injured players list. (AP Photo) (ASSOCIATED PRESS)
Through the years Montreal Canadiens' Guy Lafleur, center, team captain Serge Savard, left, and Yvan Cournoyer celebrate Lafleur's win of the Conn Smythe Most Valuable Player trophy in the team's dressing room after their Stanley Cup victory at Boston Garden in Boston, Ma., May 14, 1977. Cournoyer is on the injured players list. (AP Photo) (ASSOCIATED PRESS)
Through the years Guy Lafleur (10) of the Montreal Canadiens skates past the goal after he made his 500th goal during game between the Canadiens and the Washington Capitals at Landover, Md., Feb. 26, 1979. Trying to defend for the Capitals are goalie Bernie Wolfe and Rick Green (5). (AP Photo/William A. Smith) (William A. Smith/AP)
Through the years FILE - In this April 12, 1979, file photo, former Montreal Canadians' Jean Beliveau, left, and and Maurice Richard, right, flank Canadiens Guy Lafleur at the Forum in Montreal. (AP Photo/Doug Ball, File) (Doug Ball/AP)
Through the years Players of the Montreal Canadiens on the bench jubilate as their team defeats the New York Rangers 4-1 to win the Stanley Cup, in Montreal, Canada, May 22, 1979. From left are; Yvon Lambert, Doug Risebrough, Mario Tremblay, Pierre Mondou, and Guy Lafleur. (AP Photo) (ASSOCIATED PRESS)
Through the years Guy Lafleur (10) of the Montreal Canadiens cuts in front of Aaron Broten of the New Jersey Devils during third period NHL action at the Meadowlands Arena in East Rutherford, N.J., Dec. 20, 1983. Lafleur scored his 500th career goal as Montreal beat the Devils 6-0. (AP Photo/Bill Kostroun) (BILL KOSTROUN/ASSOCIATED PRESS)
Through the years Ex-Montreal Canadiens Guy Lafleur waits during a fundraising hockey game against ex-Quebec Nordiques on Sunday February 26, 2006, in Quebec city. (AP Photo/Clement Allard) (CLEMENT ALLARD/ASSOCIATED PRESS)
Through the years Chicago Blackhawks legend Bobby Hull shakes hands with Montreal Canadiens legend Guy Lafleur as Blackhawks Stan Mikita looks on during a pre-game cermony Tuesday, Jan. 8, 2008 in Montreal. (AP Photo/The Canadian Press, Paul Chiasson) (Paul Chiasson/ASSOCIATED PRESS)
Through the years Hockey Hall of Famer Guy Lafleur, right, arrives at the Cathedral of the Most Blessed Sacrament for the funeral of Gordie Howe, Wednesday, June 15, 2016 in Detroit. (AP Photo/Carlos Osorio) (Carlos Osorio/AP)
