William Cornwallis, English admiral and politician (d. 1819)
Admiral of the Red Sir William Cornwallis, (10 February 1744 – 5 July 1819) was a Royal Navy officer. He was the brother of Charles Cornwallis, the 1st Marquess Cornwallis, British commander at the siege of Yorktown. Cornwallis took part in a number of decisive battles including the siege of Louisbourg in 1758, when he was 14, and the Battle of the Saintes but is best known as a friend of Lord Nelson and as the commander-in-chief of the Channel Fleet during the Napoleonic Wars. He is depicted in the Horatio Hornblower novel, Hornblower and the Hotspur.

His affectionate contemporary nickname from "the ranks" was Billy Blue, and a sea shanty was written during his period of service, reflecting the admiration his men had for him.