Thomas Jenkins Semmes (December 16, 1824 – June 23, 1899) was an American politician who served as a Confederate States Senator from Louisiana from 1862 to 1865.

Due to the Union occupation of New Orleans in 1862, he resided in Richmond during the war, less than a block away from the White House of the Confederacy.

Semmes was credited with creating the motto for the Confederacy, "Deo vindice" which appears on the seal.

Senator Semmes, in proposing this motto, took pains to stress that the Confederacy had "deviated in the most emphatic manner from the spirit that presided over the construction of the Constitution of the United States, which is silent on the subject of the Deity", and he clearly expected this invocation to bring his side victory.

Semmes' home in Federal-occupied New Orleans was commandeered by order of General Benjamin Butler to quarter Union troops.

He continued to live in New Orleans, and also maintained a summer home at 191 Culpeper Street in Warrenton, Virginia, which was built in 1873.