William A. Kay (February 22, 1864 – November 27, 1931) was an American farmer and politician.

Born in Martell, Wisconsin, Kay was a farmer and served in town government.

He served in the Wisconsin State Assembly in 1909, 1911, 1915, and 1931 as a Republican.

He died in Madison, Wisconsin while still in office.

This article about a Republican Party member of the Wisconsin State Assembly born in the 1860s is a stub.