Alexander McDonald Thomson (May 20, 1822 – June 9, 1898) was an American journalist, historian, and Republican politician.

He served as the 19th Speaker of the Wisconsin State Assembly (1868–1870).

In historical documents, he is sometimes referred to as A. M. Thomson or A. McD.

Thomson was born in Pittsburgh, Pennsylvania, in 1822 to immigrants from Scotland and Holland.

Thomson also authored A Political History of Wisconsin.