Douglas Richard Brennan (born January 10, 1903, date of death unknown) was a Canadian professional hockey defenceman for the New York Rangers of the NHL. He was born in Peterborough, Ontario. Before getting to the NHL he played for including the Winnipeg Maroons of the American Hockey Association, the Kenora Thistles of the Thunder Bay Senior Hockey League, and the Vancouver Lions of the PCHL. He was acquired by the New York Rangers when they bought his professional rights from Vancouver on October 30, 1931. He would play for the team until he was released following the 1934 season. He won the Stanley Cup with New York in 1933. Following his time in New York he played 2 seasons in the CAHL his first year was spent with the Philadelphia Arrows and in his second year he played for the Spring