Thomas S. Flood (born 1840, date of death unknown) was a Union Navy sailor in the American Civil War and a recipient of the U.S. military's highest decoration, the Medal of Honor, for his actions at the Battle of Forts Jackson and St. Philip.

Born in 1840 in Ireland, Flood immigrated to the United States and was living in New York when he joined the U.S. Navy.

At the Battle of Forts Jackson and St. Philip near New Orleans on April 24–25, 1862, he stood on Pensacola's bridge and acted as an aide to the executive officer, F.A.

An artillery shell struck nearby, knocking Flood off the bridge onto the deck below and removing the leg of Signal Quartermaster Murry.

Swept from the bridge by a shell which wounded the Signal Quartermaster, Navy Boy Thomas Flood returned to the bridge after assisting the wounded man below and taking over his duties, performed them with coolness, exactitude and the fidelity of a veteran Seaman.