| Position: | Defence |
| Shoots: | Left |
| Height Ft: | 5 |
| Height In: | 8 |
| Weight Lb: | 215 |
| Birth Date: | February 1, 1915 |
| Birth Place: | Brockville, Ontario, Canada |
| Career Start: | 1935 |
| Career End: | 1949 |
Michael Clarence McMahon Sr. (February 1, 1915 – December 3, 1974) was a Canadian professional ice hockey player who played 57 games in the National Hockey League between 1943 and 1946. Born in Brockville, Ontario, he played for the Montreal Canadiens and Boston Bruins. He won the Stanley Cup in 1944 with the Montreal Canadiens. His son Mike McMahon Jr. also played in the NHL.
| Regular season | Playoffs | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Season | Team | League | GP | PIM | GP | G | A | Pts | PIM | |||||
| 1935–36 | Brockville Magedomas | LOVHL | 17 | 11 | 8 | 19 | 27 | 7 | 6 | 3 | 9 | 8 | ||
| 1935–36 | Brockville Magedomas | Al-Cup | — | — | — | — | — | 6 | 3 | 3 | 6 | 13 | ||
| 1936–37 | Cornwall Flyers | LOVHL | 17 | 7 | 13 | 20 | 48 | 6 | 2 | 2 | 4 | 6 | ||
| 1937–38 | Cornwall Flyers | LOVHL | 24 | 17 | 17 | 34 | 34 | 11 | 6 | 4 | 10 | 33 | ||
| 1937–38 | Cornwall Flyers | Al-Cup | — | — | — | — | — | 11 | 6 | 4 | 10 | 33 | ||
| 1938–39 | Cornwall Flyers | LOVHL | 38 | 20 | 34 | 54 | 144 | 9 | 3 | 5 | 8 | 22 | ||
| 1939–40 | Cornwall Flyers | QSHL | 30 | 2 | 7 | 9 | 81 | 5 | 2 | 3 | 5 | 14 | ||
| 1940–41 | Quebec Aces | QSHL | 33 | 5 | 11 | 16 | 57 | 4 | 1 | 1 | 2 | 4 | ||
| 1941–42 | Quebec Aces | QSHL | 40 | 16 | 11 | 27 | 76 | 7 | 4 | 2 | 6 | 14 | ||
| 1941–42 | Quebec Aces | Al-Cup | — | — | — | — | — | 6 | 1 | 3 | 4 | 18 | ||
| 1942–43 | Quebec Aces | QSHL | 33 | 6 | 24 | 30 | 73 | 4 | 1 | 2 | 3 | 20 | ||
| 1942–43 | Ottawa Commandos | QSHL | — | — | — | — | — | 2 | 0 | 2 | 2 | 0 | ||
| 1942–43 | Montreal Royals | QSHL | — | — | — | — | — | 1 | 0 | 0 | 0 | 2 | ||
| 1942–43 | Montreal Canadiens | NHL | 1 | 0 | 0 | 0 | 0 | 5 | 0 | 0 | 0 | 14 | ||
| 1943–44 | Montreal Canadiens | NHL | 42 | 7 | 17 | 24 | 86 | 8 | 1 | 2 | 3 | 16 | ||
| 1944–45 | Montreal Royals | QSHL | 10 | 6 | 16 | 22 | 58 | 7 | 1 | 2 | 3 | 8 | ||
| 1945–46 | Montreal Canadiens | NHL | 13 | 0 | 1 | 1 | 2 | — | — | — | — | — | ||
| 1945–46 | Boston Bruins | NHL | 2 | 0 | 0 | 0 | 2 | — | — | — | — | — | ||
| 1945–46 | Buffalo Bisons | AHL | 26 | 2 | 14 | 16 | 50 | 12 | 5 | 1 | 6 | 14 | ||
| 1946–47 | Dallas Texans | USHL | 13 | 1 | 3 | 4 | 43 | — | — | — | — | — | ||
| 1946–47 | Buffalo Bisons | AHL | 50 | 12 | 28 | 40 | 68 | 4 | 1 | 0 | 1 | 4 | ||
| 1947–48 | Houston Huskies | USHL | 39 | 7 | 11 | 18 | 91 | — | — | — | — | — | ||
| 1947–48 | Buffalo Bisons | AHL | 17 | 2 | 9 | 11 | 15 | 8 | 0 | 2 | 2 | 16 | ||
| 1948–49 | Springfield Indians | AHL | 16 | 2 | 4 | 6 | 14 | — | — | — | — | — | ||
| AHL totals | 109 | 18 | 55 | 73 | 147 | 24 | 6 | 3 | 9 | 34 | ||||
| QSHL totals | 146 | 35 | 69 | 104 | 345 | 30 | 9 | 12 | 21 | 62 | ||||
| NHL totals | 58 | 7 | 18 | 25 | 90 | 13 | 1 | 2 | 3 | 30 | ||||