Thomas Island () is a large island in Highjump Archipelago, 6 nautical miles (11 km) long and from 1 to 3 nautical miles (6 km) wide, lying near the center of the main cluster of islands off the north flank of the Bunger Hills. Mapped from air photos taken by U.S. Navy Operation Highjump, 1946-47, and named by the Advisory Committee on Antarctic Names (US-ACAN) for Lieutenant (j.g.) Randolph G. Thomas, U.S. Navy, hydrographic officer with U.S. Navy Operation Windmill, 1947-48, who served as surveyor with the astronomical control parties.
This article incorporates public domain material from the United States Geological Survey document "Thomas Island" (content from the Geographic Names Information System).