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Shanahan, 45, will oversee all operations for the Maple Leafs, from both the hockey and business perspectives.
The Etobicoke, Ont., native played 1,524 NHL games with New Jersey, St. Louis, Hartford, Detroit and the New York Rangers, earning entry into the Hall of Fame last November with 656 goals and 698 assists in his regular-season career.
Shanahan won three Stanley Cups as a member of the Red Wings and a gold medal with Canada at the 2002 Olympics.
After retirement, he joined the NHL’s head office in December 2009 as vice president of hockey and business development, later moving to the position of chief disciplinarian for the league.
The NHL announced last week that former player Stephane Quintal will handle Shanahan's role at the Department of Player Safety through the playoffs.
The Maple Leafs appeared to be headed for a second straight playoff berth for much of this season, but a late-season swooned knocked them down to a 12th-place finish in the Eastern Conference.