William H. Thomas (September 25, 1821 – December 26, 1898) was an American lawyer, Democratic politician, and Wisconsin pioneer.
Thomas was born on September 25, 1821, in Clinton County, New York, and received a liberal education.
After the legislative term, he enrolled as a volunteer for service with the Union Army and was enlisted as a private in the Company D of the 3rd Wisconsin Cavalry Regiment.
The 3rd Wisconsin Cavalry served primarily in the Trans-Mississippi theater of the war, engaged in suppression of guerilla activity in Kansas, Missouri, and Arkansas.
[1] He was elected district attorney of Waukesha County in 1879 and was re-elected in 1881 and 1884, serving seven consecutive years in the office.