William S. Barry (born William Taylor Sullivan Barry; December 10, 1821 – January 29, 1868) was an American politician who served as a Deputy from Mississippi to the Provisional Congress of the Confederate States from 1861 to 1862.

Born in Columbus, Mississippi, William S. Barry graduated from Yale College in 1841 and was initiated into Skull and Bones Society in his last year.

During the American Civil War he enlisted in the Confederate States Army and raised the 35th Mississippi Infantry Regiment, at times acting as brigade commander.

He broke parole and commanded his regiment, and at times Sears's Brigade, during the Atlanta Campaign.

After his release, Barry resumed the practice of law in Columbus, where he died on January 29, 1868.