Robert Carter Nicholas (1793 – December 24, 1857) was a United States Senator from Louisiana. Born in Hanover, Virginia, he served in the War of 1812 as a captain and major. He attended the College of William and Mary in Williamsburg, Virginia, and moved to Louisiana, where he became a sugar planter in Terrebonne Parish in 1820. Nicholas was a nephew of John Nicholas a U.S. Representative and Wilson Cary Nicholas, a U.S. Senator and Representative, both of Virginia. Robert Nicholas was the son of George Nicholas (1754–1799) and grandson of Robert Carter Nicholas (1728–1780).