Many players wore the number 12 in the Toronto Maple Leafs line. However, the most recent player wearing the number 12 is Tim Connolly. Tim Connolly is the starting center for the Toronto Maple Leafs on their first line.
Carlos Delgado wore the number when he played for Toronto from 1993 to 2004.
Gary Roberts wore #10 for the Calgary Flames, Tampa Bay Lightning, and the Pittsburg Penguins and #7 for the Toronto Maple Leafs
there are over twenty but only three wore 13 on their jersey
Wilf Paiement wore #99 in the late 70s, early 80s, long before Gretzky made it famous
John Kordic wore #31 with the Montreal Canadiens and he wore #27 with the Toronto Maple Leafs. He wore #44 when he played for the Quebec Nordiques and #25 with the Washington Capitals
Gordie Nelson
According to hockey-reference.com (link below), Kirk Muller wore number 21 for the Toronto Maple Leafs from 1996-97, and only wore number 9 with the New Jersey Devils (1986-91), New York Islanders (1995-96), and Florida Panthers (1997-99) Kirk Muller's hockey-reference page: http://www.hockey-reference.com/players/m/mulleki01.html
Alomar wore #12
Chauncey Billups wore #3 for the 1997-98 season in Toronto
Felton wore #2 in his brief time with New York. He will likely keep that number as Landry Fields (who last wore it) has moved to Toronto.
Big Zee wore number 19 for the Argonauts.
Borje Salming wore number 21 for the Toronto Mapleleafs. However, he left the team in 1989 and his number 21 was taken by a future NHL star named Sean McKenna.