Nathan Clifford, American lawyer, jurist, and politician, 19th United States Attorney General (d. 1881)
Nathan Clifford (August 18, 1803 – July 25, 1881) was an American statesman, diplomat and jurist.

Clifford is one of the few people who have served in all three branches of the U.S. federal government. He represented Maine in the U.S. House of Representatives from 1839 to 1843, then served in the administration of President James K. Polk as the U.S. Attorney General from 1846 to 1848 and as the U.S. Ambassador to Mexico from 1848 to 1849. In the latter office, he signed the Treaty of Guadeloupe Hidalgo. In 1858, President James Buchanan appointed Clifford to be an associate justice of the U.S. Supreme Court. Clifford served on the Supreme Court until his death in 1881.