Lieutenant Alfred Douglas Douglas-Hamilton, 13th Duke of Hamilton and 10th Duke of Brandon TD, DL (6 March 1862 – 16 March 1940) was a Scottish nobleman and sailor.
Hamilton was born at Shanklin, Isle of Wight in 1862, the son of Captain Charles Douglas-Hamilton (1808–1873), a great-great-grandson of the 4th Duke of Hamilton. He served as a young man in the Royal Navy, and gained a reputation for being able to dive under the keels of the battleships on which he served, without any equipment, reappearing on the opposite side of the ship to the amazement of his crewmates. He was persuaded to leave in 1888 by his fourth cousin the twelfth Duke in 1890. There was a quite serious possibility that Alfred would provide a good match for the heirless twelfth duke's daughter, Lady Mary. These hopes of maintaining continuity were dashed however in 1890, when Hamilton was partially paralysed by a rare tropical disease he had caught whilst on his last tour of duty. Hamilton recovered however and succeeded in 1895. Whilst inheriting all entailed property and assets from his cousin and a £1 million debt, a large share of the Hamilton lands and properties went to Lady Mary, latterly the Duchess of Montrose. The properties that left the Hamilton family at this time included Brodick Castle on Arran, which had been owned by the Hamiltons for 500 years.
One property that did not leave the family was Hamilton Palace, the main family seat. However, the Duke had offered the palace to the Navy during World War I for use as a hospital. Following the end of the war it was considered necessary to demolish it due to subsidence, blamed on the family's own coal mines. Hamilton moved to Dungavel House, which had previously been a Hamilton shooting lodge on moorland close to Strathaven.