Lucius Quintus Cincinnatus Lamar (1825-1893) was a US statesman who gained fame for his persistent efforts to reconcile the North and the South after the Civil War.

Lamar was born in Eatontan, Georgia, the son of a wealthy plantation owner. After graduating from Emory College in 1845 he studied law, gaining admission to the bar in 1847. After practicing law in Covington, GA for a few years he ran for the Georgia state legislature and was elected, serving for 1853-54 session. In 1855 he went west, as did many rising young men of his day, settling in Oxford, Mississippi, where he joined the faculty of the University of Mississippi.

In 1857 Lamar won a seat in the House of Representatives as a Democrat, which he held for three years. But upon the outbreak of the Civil War Lamar immediately resigned and returned home. Initially Lamar had opposed secession by Southern States from the Union, but as war clouds gathered he reversed course, and was ultimately selected to draft Mississippi's secession declaration. Lamar now became one of the most ardent and prominent Confederate voices. Lamar used his wealth and connections to organize the 19th Mississippi Volunteers, which he commanded, seeing action in the Peninsula campaign.

In late 1862, President Jefferson Davis selected Lamar to become the Confederate States ambassador to Russia. Lamar made it as far as Paris before he was recalled, Russia having refused to recognize the sovereignty of the CSA.

After his return from Europe, Lamar served as legal council and political spokesman to Jefferson Davis, worked as a judge advocate in Confederate military trials, and served as an aide to General James Longstreet.

Lamar returned to Mississippi after the war, resuming his law practice and teaching position at the university, directing the law department until 1870. That year Mississippi was readmitted to the Union, and Lamar received a full pardon for his services to the Confederacy. In 1872 he was re-elected to the House of Representatives.

In Congress Lamar worked to repair some of the damage caused in the previous decade by the Radical Reconstructionists, famously calling for amnesty for all former confederates. Tired of the animosity of the radicals, many people in both the North and South supported this position, and it gained Lamar much popularity.

With Lamar's political fortunes on the rise, the Mississippi legislature sent him to the Senate in 1877, where he continued his efforts to foster peace and harmony between the North and South. When Grover Cleveland achieved the first democratic presidency since before the war in 1884, he appointed Lamar to his cabinet as Secretary of the Interior. Three years later, Cleveland nominated him as a Supreme Court justice, and the Senate confirmed him on January 16, 1888. As a supreme court justice, he continued to uphold the causes he had supported all his life, ruling in favor of economic nationalism and states rights, and working to limit the power of the federal government, particularly its ability to enforce civil rights. Lamar died on January 23, 1893, at the age of 67.