John Osmael Scott-Ellis, 9th Baron Howard de Walden, 5th Baron Seaford TD (27 November 1912 – 10 July 1999) was a British peer, landowner, and a Thoroughbred racehorse owner/breeder. He was the son of Margarita van Raalte and her husband, Thomas Scott-Ellis, 8th Baron Howard de Walden, whose London home was Seaford House in Belgravia; and he was educated at Eton College and Magdalene College, Cambridge.
In 1931, he moved to Munich to learn a language, where he bought a car. On his first day behind the wheel, he claimed to have knocked over a pedestrian - Adolf Hitler. He served in the Territorial Army in the Westminster Dragoons, rising to the rank of major. He inherited Dean Castle in Kilmarnock, East Ayrshire, Scotland which, along with his father's collections of arms and armour, and his grandfather's collection of musical instruments, he gave to the people of Kilmarnock in 1975.