William Robertson Warren (October 9, 1879 – December 31, 1927) was a Newfoundland lawyer, politician and judge who served as the dominion's Prime Minister from July 1923 to April 1924.

The next year Squires was forced to resign and Warren was chosen the party's new leader and prime minister.

His government launched a formal inquiry into the corruption charges which resulted in the arrest and conviction of Squires and several others.

Warren moved to the opposition benches and formed a coalition with Tory William J. Higgins to form the new Liberal-Conservative Progressive Party that won the election a few weeks later making the conservative Walter Stanley Monroe the new prime minister.

He was married first to Ethel Alice Gordon, by whom he had one son, John Henry Warren, and two daughters.