Cyril Joseph Denneny (December 23, 1891 – September 10, 1970) was a Canadian ice hockey forward who played for the Ottawa Senators and Boston Bruins in the National Hockey League from 1917 to 1929 and the Toronto Blueshirts of the National Hockey Association from 1914 to 1917. He won the Stanley Cup five times, four times with Ottawa and once with Boston, and was inducted into the Hockey Hall of Fame in 1959.
His younger brother Corbett Denneny also played in the NHL.