In J.R.R. Tolkien's Middle-earth legendarium, Déor was the seventh King of Rohan. He was born during the rule of his great-great-grandfather Aldor the Old, so that the unique situation where five generations where living in one house occurred. He became King at the death of his father Goldwine in 2699 T.A.
During Déor's realm the Dunlendings began to cause trouble again; they had slowly returned to Rohan under Goldine's reign, after Aldor had driven them out long before. Déor rode north to fight them, but he learned that the Gondorian fortress of Isengard had fallen under Dunlendish rule. Isengard was impregnable, so Déor had to accept for the time being a northern threat to his realm.
Déor died in 2718 after a troublesome rule of nineteen years, and was followed by his son Gram.
