William Kenneth Russell Mallen (October 4, 1884 – April 23, 1930) was a Canadian professional ice hockey player.

He won two Stanley Cups in his career, in 1910 with the Ottawa Senators, and in 1915 with the Vancouver Millionaires.

Born in Morrisburg, Ontario, Mallen played one season with Cornwall of the Federal Amateur Hockey League (FAHL) before turning professional with the Calumet Miners of the International Professional Hockey League (IPHL) in 1904.

Ken Mallen was known as one of the speediest players of his era and he was also a capable goal scorer.

[1] During the 1912–13 PCHA season Mallen won a speed skating contest against fellow PCHA players Moose Johnson, Si Griffis and Cyclone Taylor, all of them considered to be among the quickest players in the game at the time.