Lyman Wellington Thayer (October 30, 1854 – February 8, 1919) was an American farmer and Republican politician from the U.S. state of Wisconsin.

He was the 38th mayor of Ripon, Wisconsin, (1916–1918) and represented Fond du Lac County in the Wisconsin State Senate and Assembly during the 1890s.

Thayer was born on October 30, 1854, in Wausau, Wisconsin.

[4] Thayer was Chairman of Ripon and of the Fond du Lac County, Wisconsin Board of Supervisors.

[4] After leaving the Senate, he served as mayor of Ripon from 1916 to 1918.