Silas Dennison McLellan, CM (17 March 1897 – 10 February 1974) was a Canadian marathon runner.

Military Service Silas was drafted on the 11th of June 1918 at Camp Aldershot.

He remained in the United Kingdom until June 1919 when he returned to Canada and was discharged on the 5th of July 1919 in Halifax, Nova Scotia.

Silas competed in the 1928 Olympics and beat Clarence DeMar, five-time winner of the Boston Marathon.

In the same year, Silas McLellan finished sixth in the 1930 British Empire Games marathon.