John McDermeid Gearin (August 15, 1851 – November 12, 1930) was an American politician and attorney from the state of Oregon.

Originally an independent politician, he later became a Democrat and lost an election to serve in the United States Congress before winning appointment to the Senate in 1905.

[2] After attending the local public schools, Gearin enrolled at St. Mary's College in San Francisco from 1863 to 1867.

[3] In 1873, he was admitted to the Oregon bar after studying law, and then entered private legal practice in Portland at what is now Miller Nash Graham & Dunn LLP.

[2] Gearin was appointed by U.S. President Grover Cleveland in 1893 as special prosecutor for the government concerning cases of opium fraud.