William A. Adamson (May 5, 1834 – March 1, 1907) was a Canadian American immigrant, farmer, and Republican politician.
He served one term in the Wisconsin State Assembly, representing western Fond du Lac County.
He emigrated to the United States with his parents in 1837, settling in Jefferson County, New York.
He received a common school education until age 14, when he joined the crew of a ship.
He became associated with the Republican Party and, in 1879, he was elected assistant sergeant-at-arms of the Wisconsin State Assembly.