Harold William Hounsfield Riley Sr. (December 15, 1877 – January 1, 1946) was a member of the Legislative Assembly of Alberta.

On October 31, 1911 after the death of Archibald McArthur, Mr. Riley ran for the Conservative Party, in what would be known as the brothers by-election.

During the 1913 he ran in Bow Valley, he was defeated by George Lane from the Liberal party.

He was married to Maude Riley (née Keen) in 1907,[1] who is best known for convincing the Calgary Police Force to hire women in 1913.

After the war he helped found the Southern Alberta Pioneers' and Old Timers' Association, and he served as secretary from 1921 to 1943.