T. Harry Williams (Thomas Harry Williams) was an historian at Louisiana State University in Baton Rouge whose writing career began in 1941 and extended for thirty-eight years until his death in 1979. Williams is perhaps best known for his American Civil War study, Lincoln and His Generals, a "Book of the Month" selection from 1952, and Huey Long, winner of both the National Book Award and the Pulitzer Prize in 1970.

Williams passed away approximately two months after retirement due to complications from pneumonia.

In 1998, Williams was posthumously inducted into the Louisiana Political Museum and Hall of Fame in Winnfield.