Ellsworth, Lincoln (1880-1951), a United States explorer. He made early flights over the Arctic, and made the first flight across Antarctica.

His first Arctic flight, in 1925, was an attempt with Roald Amundsen to fly over the North Pole. Their planes were forced down, and they were stranded on the ice for 25 days before being able to return to Svalbard. In 1926 Ellsworth, Amundsen, and Umberto Nobile flew the dirigible Norge from Svalbard to Alaska over the North Pole. In 1935 Ellsworth made the first flight across Antarctica, traveling 2,300 miles (3,700 km) from the Weddell Sea to the Ross Sea in his plane Polar Star, and claiming 300,000 square miles (770,000 km2) of territory for the United States. (The United States, however, does not recognize the claims Ellsworth made for it.)

Ellsworth was born in Chicago and attended Yale and Columbia universities. In 1903 he went to Canada as a surveyor for a railway company, and then worked as a mine and survey engineer in Canada and Alaska. He also worked for the United States Geological and Biological surveys. In 1924 he led an expedition through the Andes to the headwaters of the Amazon.

Ellsworth's books include: The Last Wild Buffalo Hunt (1915); First Crossing of the Polar Sea (with Roald Amundsen, 1927); Search (1932); Exploring Today (1935); and Beyond Horizons (1938).