Born in Peterborough, Ontario, was a star multi-sport athlete. In addition to playing hockey, Mahoney was also a renowned lacrosse player, a Canadian football quarterback, and a softball pitcher. He was part of the Peterborough Shamrocks bantam "A" team, which won the 1953 provincial championship. In 1956, he became the first local native to play for the Peterborough Petes, and he served as captain of this junior "A" squad during the 1958 season. Mahoney later played university hockey at Carlton University in Ottawa and at McMaster University in Hamilton.
In 1963, Mahoney led the McMaster Marlins to becoming the first ever Canadian Intercollegiate Athletic Union (CIAU) ice hockey champions, at the inaugural CIAU University Cup tournament, also winning the first ever tournament Most Valuable Player award.
Although Mahoney never played pro hockey, he had a long coaching career, serving 16 years behind the bench with the McMaster University squads. In 1980, he was hired as an assistant coach with the Washington Capitals, but he was released as part of a 1981 clearing of the coaching staff. In 1982, he became coach of the Adirondack Red Wings of the AHL before gaining his position with Minnesota of the NHL.
NHL Coaching record
|Team||Year||Regular season||Post season|
|Minnesota North Stars||1983–84||80||39||31||10||88||1st in Norris||Lost in Conference Finals|
|Minnesota North Stars||1984–85||13||3||8||2||(62)||4th in Norris||(fired)|
- "William (Bill) Mahoney". Peterborough and District Sports Hall of Fame & Museum. 2013-05-22. Retrieved 2013-10-24.
- "William (Bill) Mahoney". Peterborough and District Sports Hall of Fame & Museum. 1982. Retrieved 2021-02-09.
- "Major W.J. 'Danny' McLeod Award (University Cup Tournament MVP)" (PDF). U Sports. Retrieved 2021-02-09.
- Kane, Mike (1983-06-01). "Mahoney Bound for Minnesota". The Daily Gazette. Schenectady, New York. p. 14. Retrieved 2013-10-24 – via Google News Archive.
| Head coach of the Minnesota North Stars