William Lair Thompson (January 1, 1880 – August 5, 1940), known as Lair Thompson or W. Lair Thompson, was an American politician and lawyer from the state of Oregon. He served one term in the Oregon House of Representatives followed by a four-year term in the Oregon State Senate. Thompson was a conservative Republican who represented a large rural district. He served as President of the Oregon Senate during the 1915 legislative session. Thompson was one of Oregon's most prominent trial attorneys, handling a number of high-profile cases including one, Bunting v. Oregon, that required him to present arguments before the United States Supreme Court.