Master
From Tolkien Gateway
A title used most commonly for the ancient and powerful being known to the Elves as Iarwain Ben-adar, and to the hobbits as Tom Bombadil, whose jolly and riddling songs gave him mastery over all things in his domain. Though the title 'Master' is almost always used as a reference to Tom, there is one exception: the Orc Uglúk used the title of his own Master, the Wizard Saruman.