Frank Alexander McLain (January 29, 1852 – October 11, 1920) was a U.S. Representative from Mississippi.

Born near Gloster in Amite County, Mississippi, McLain attended the public schools, and was graduated from the University of Mississippi at Oxford in 1874.

He was admitted to the bar and commenced practice in Liberty, Mississippi, in 1880.

McLain was elected as a Democrat to the Fifty-fifth Congress to fill the vacancy caused by the death of William F. Love.

He was reelected to the Fifty-sixth and to the four succeeding Congresses and served from December 12, 1898, to March 3, 1909.