Sir William Pollard Byles (13 February 1839 – 15 October 1917) was a British newspaper owner and radical Liberal politician.

Born in Bradford, Yorkshire, in 1839, W P Byles was the son of William Byles, proprietor of the Bradford Observer and Anna Holden of Halifax.^[1] He eventually succeeded his father as owner of the newspaper, which had been renamed the Yorkshire Observer. He married Sarah Anne Unwin of Colchester in 1865. They had no children. He was knighted in 1911.

In 1892 he was elected as Liberal Member of Parliament for Shipley. Upon election he became a member of the Interparliamentary Union for Peace and Arbitration.^[2] He lost his seat three years later to Fortescue Flannery, his Conservative opponent. Byles was a pacifist, and actively opposed the Second Boer War. In 1900 he stood on an anti-war ticket as Labour Representation Committee candidate at Leeds East, but was defeated. He returned to the Commons at the 1906 general election as Liberal MP for Salford North. He was an advanced radical, a strong supporter of Irish Home Rule and an advocate of Land Reform.^[1] Byles retained his seat until his death.