John Randolph Thornton (August 25, 1846 – December 28, 1917) was a United States senator from Louisiana.

He enlisted in the Confederate States Army and served until the close of the Civil War in Company B, Second Louisiana Cavalry.

[1][2] He engaged in agricultural pursuits until 1877, studied law, was admitted to the bar in 1877 and commenced practice in Rapides Parish.

[1] Thornton was appointed as a Democrat to the U.S. Senate on August 27, 1910, and was subsequently elected[2] to fill the vacancy caused by the death of Samuel D. McEnery, serving from December 7, 1910, to March 3, 1915; he was not a candidate for reelection to the Senate.

He was appointed by President Woodrow Wilson a member of the Board of Ordnance and Fortification and served from 1915 to 1917, and resumed the practice of law in Alexandria, Louisiana; he died there in 1917.