Martin Welker (April 25, 1819 – March 15, 1902) was a lawyer, politician, and judge from Ohio. Welker served three terms as a Republican member of the House of Representative, winning election in 1864, 1866, and 1868. Following his retirement from Congress, Welker was appointed a federal judge for the Northern District of Ohio by President of the United States Ulysses S. Grant in 1873, remaining in that post until his retirement in 1889.