USS Harold C. Thomas (DE-21) was an Evarts-class destroyer escort constructed for the United States Navy during World War II.

After three voyages escorting merchantmen from San Francisco, California, to Pearl Harbor, Harold C. Thomas served with ComSubTraPac from 2 to 20 November 1943.

Returning to Pearl Harbor on 6 May, the destroyer escort spent the remainder of the year in the vital but unsung work of shepherding merchantmen, cargo ships, and transports through the back staging area, up to their assembly points for invasion forces.

On 21 November Harold C. Thomas rescued seven men from a PBM flying boat which had crashed at sea off Majuro Atoll.

Harold C. Thomas returned to Pearl Harbor on 5 April and spent the rest of the war in submarine training and escort duty.