Cornelius Dennis "Mad Dog" Madigan (October 4, 1934 – January 2, 2024) was a Canadian professional ice hockey defenceman.

He played 20 games in the National Hockey League with the St. Louis Blues during the 1972–73 season.

Cornelius Dennis Madigan was born in Port Arthur, Ontario on October 4, 1934.

[1] At the time of his retirement, Madigan was second in minor league history in career penalty minutes.

[2] In addition to Madigan's hockey career, he had a minor role in the 1977 cult classic movie Slap Shot as legendary hockey goon Ross "Mad Dog" Madison.