Captain Henry Duncan (24 November 1735 – 7 October 1814)[a] was an officer of the Royal Navy, who saw service in the American War of Independence.

Duncan began his sea life in the merchant service, possibly in that of the East India Company, but entered the Royal Navy on in 1755 joining HMS Nassau.

Duncan already had an older son, Henry, who later served in the Navy from 1781 until being lost off the coast of Newfoundland in 1802 with HMS Scout.

In January, 1776, William Howe was appointed as Commander-in-Chief of British forces in North America and chose Duncan to join him as flag captain of HMS Eagle.

On the commands of General Howe, Duncan commanded an invasion fleet of 26 ships carrying 2,000 men led by General William Tryon from New York to Westport, Connecticut, to raid Continental Army supply depots in Danbury, Connecticut, on 22 April 1777, resulting in the Battle of Ridgefield.