William Scarlett, 3rd Baron Abinger

Lieutenant-General William Frederick Scarlett, 3rd Baron Abinger, CB (1826–1892), was a British peer.

Scarlett succeeded his father Robert Scarlett, 2nd Baron Abinger, in 1861. Educated at Eton College and Trinity College, Cambridge, the 3rd Baron became an officer of the Scots Fusilier Guards regiment of the British Army. He served in the Crimean War fighting in the Battle of Alma, the Battle of Balaclava and the Battle of Inkerman. He also visited the United States during the American Civil War.

In 1863 he married Helen Magruder, daughter of Commodore George Allan Magruder, of the United States Navy. They had one son, James, who became Baron at his father's death. Their daughter Evelina married Major Henry Haverfield was a suffragette and an aid worker during World War I.

Scarlett's first cousin once removed, James Williams Scarlett, son of Sir William Anglin Scarlett, purchased the isle of Gigha, off the coast of Argyll, for £49,000 in 1865. His son, Lieutenant-Colonel William James Scarlett, then built the mansion house of Achamore there and Gigha remained in the family's hands until 1919.