Lucius Quintus Cincinnatus Lamar II, American lawyer and politician, 16th United States Secretary of the Interior (b. 1825)
Lucius Quintus Cincinnatus Lamar II (September 17, 1825 – January 23, 1893) was an American politician, diplomat, and jurist. A member of the Democratic Party, he represented Mississippi in both houses of Congress, served as the United States Secretary of the Interior, and was an Associate Justice of the Supreme Court of the United States. He also served as an official in the Confederate States of America.

Born and educated in Georgia, he moved to Oxford, Mississippi to establish a legal practice. He was elected to the United States House of Representatives in 1856 and served until December 1860, when he helped draft Mississippi's Ordinance of Secession. He helped raise the 19th Mississippi Infantry Regiment and worked on the staff of his wife's cousin, General James Longstreet. In 1862, Confederate President Jefferson Davis appointed Lamar to the position of Confederate minister to Russia. Following the Civil War, Lamar taught at the University of Mississippi and was a delegate to several state constitutional conventions.

Lamar returned to the United States House of Representatives in 1873, becoming the first Mississippi Democrat elected to the House since the end of the Civil War. He remained in the House until 1877, and represented Mississippi in the Senate from 1877 to 1885. He opposed Reconstruction and initially voting rights for African Americans but later came to support black suffrage and opposed the 1890 Mississippi Constitution. In 1885, he accepted appointment as Grover Cleveland's Secretary of the Interior. In 1888, the Senate confirmed Lamar's nomination to the Supreme Court, making Lamar the first Southerner appointed to the court since the Civil War. He remained on the court until his death in 1893.