William Renwick Riddell (6 April 1852 – 18 February 1945) was a Canadian lawyer, judge, and historian.

[2] In 1892, he attempted to prevent the Law Society of Upper Canada from admitting Clara Brett Martin to the bar of Ontario.

[4] He was the trial judge in Sero v Gault, where Eliza Sero, a Mohawk woman, argued that her fishing net had been illegally seized by Thomas Gault, a government fisheries inspector, because the Haudenosaunee were sovereign over the land on which she lived.

[7] As a historian, he published numerous works of legal, medical, and social history, including biographies of William Kirby and John Graves Simcoe.

[12] Riddell was not well-liked: William Mulock thought him a "terrible man", while according to John Josiah Robinette, "everyone hated the old boy".