Thaddeus E. Cromley (21 June 1843 – 20 April 1921) was a Democratic politician from Ohio.

Thaddeus Cromley descended from German immigrants named Grammlich, who settled in Pennsylvania in 1749.

[1] He attended the local log schoolhouse, and he studied at Circleville Union School beginning at age 16.

[4] In 1892, Cromley was appointed by Governor McKinley as a trustee of the Boy's Industrial School in Fairfield County.

In the latter term he was President Pro Tempore and chairman of the Committees on Finance and Rules.