Mike McMahon Sr. played just 57 games in his NHL career. The vast bulk of that came in his only full campaign, 1943-44, when he was essentially a war fill-in, as many NHLers enlisted for service in World War II.. Listed at 5'9" and 218lbs, McMahon played in 42 games that season, scoring 7 goals and 24 points. He added another goal and three points in 8 playoff games, helping the Canadiens win the Stanley Cup.
McMahon, a Quebec Senior League stalwart, was an adventurous sort. He made the opposition feel quite uncomfortable, as his career 132 penalty minutes suggested. But he also made his own goaltender uncomfortable. Bill Durnan shared this memory of McMahon in Stan and Shirley Fischler's book Heroes and History:
"Mike McMahon, a rolypoly who would scare the hell out of me whenever he played the point; I always expected the other team to jab the puck away from him and come in on me all alone."
Once the war was over and NHL rosters were at full power once again, McMahon found himself mostly playing in the American Hockey League until his retirement in 1949. He became a self-employed welder after leaving the ice.
Mike McMahon Sr. died on December 3rd, 1974. Mike's son Mike Jr. also played in the National Hockey League, playing in 224 games in the 1970s.