Ice hockey does not have any formalized uniform numbering rules. Historically, in the National Hockey League, starting goaltenders wore Number 1, the backup goalie wore Number 30, and the other players (the "skaters") wore low numbers (generally Number 2-Number 28). It is still traditional for goaltenders to wear either Number 1 or numbers near Number 30 (in a range from approximately Number 29 to Number 35.) Some well-known goalies with non-traditional numbers include José Théodore (Number 60) and Ron Hextall (Number 27; Number 72 when Number 27 was unavailable). Evgeni Nabokov and Ed Belfour have both worn Number 20 in honor of their mentor, legendary Russian goalie Vladislav Tretiak.
In recent years, it has become more common for players to wear numbers in the 30s and above. This is due in part to many teams having retired lower numbers. The Montreal Canadiens, for example, have only three single-digit numbers left un-retired.
A number of players have worn higher numbers up through Number 99 (though Number 99 itself is now retired league-wide in the NHL to honor Wayne Gretzky). For example, Jaromir Jagr wore Number 68 in honor of the year of the Prague Spring in 1968 and his grandfather's death; Alexander Mogilny wore Number 89 to honor the year he defected to the United States from the former Soviet Union; and Sidney Crosby wears Number 87 because his birth date is August 7, 1987, written "8/7/87" in the U.S. date format.
Doubling of a single-digit number has occasionally been used for players whose numbers were unavailable. For example, Phil Esposito switched to Number 77 when he joined the New York Rangers where Number 7 was worn by Rod Gilbert; and Ray Bourque, who succeeded Esposito in wearing Number 7 for the Boston Bruins, switched to Number 77 to allow the Bruins to retire Esposito's original Number 7. That same season, Paul Coffey switched to Number 77 when he was traded from Edmonton to Pittsburgh. In addition, Gretzky wore Number 99 because Number 9, which he wore in tribute to Gordie Howe, was taken on his junior team. Going the other way, Todd Bertuzzi, who wore Number 44 for many years, switched to Number 4 when he was traded to the Anaheim Ducks in 2007, since Number 44 was already in use by alternate captain Rob Niedermayer.
#84 was the final number to have never been worn NHL, until Canadiens forward Guillaume Latendresse first wore the number on September 29, 2006. The last player to wear a form of zero in the NHL was Martin Biron, who wore Number 00 with the Buffalo Sabres in three games in 1995-96. By the time he returned to the Sabres in 1998, the NHL had changed its rules to disallow the number, and he was not allowed to grandfather his previous jersey number. He instead changed to Number 43, which he wears to this day.
After the death of Mark Bavis in the September 11, 2001 terrorist attacks, the ECHL's South Carolina Stingrays retired Number 12 in his honor. Bavis had played from 1994-96, and wore Number 12 for the majority of his career. When the Stingrays retired Number 12, Ryan Brindley, who had worn Number 12 during the 2001 Kelly Cup season, switched from Number 12 to Number 55 for the rest of his stint with the Stingrays.