Thaddeus Maclay Mahon (born May 21, 1840) was a Republican member of the United States House of Representatives from Pennsylvania. He represented Pennsylvania’s 17th Congressional District and served as a federal legislator during the late nineteenth and early twentieth centuries. A male officeholder identified with the Republican Party, Mahon’s congressional service placed him among the historical members of Congress from his state.

Mahon served as a Representative from August 7, 1893, until March 3, 1907, completing seven terms in the U.S. House of Representatives. During this period, he was in office continuously, reflecting sustained support from his constituents in Pennsylvania’s 17th District. Although specific committee assignments, legislative initiatives, and other roles are not detailed in the available record, his long tenure indicates a stable presence in Congress over nearly fourteen years.

After March 3, 1907, Mahon left office and is recorded as a former member of Congress. No additional official positions, contact information, or personal details are provided in the available metadata.