Tom Bombadil
Old Man Willow, along with the Barrow-wight and Tom Bombadil himself, first appeared in Tolkien's narrative poem "The Adventures of Tom Bombadil", where Old Man Willow trapped Bombadil himself briefly. Willow is portrayed as a sentient and evil willow tree with various powers including hypnosis and the ability to move his roots and trunk. Some characters of the story speculate that he may have been related to the Ents, or possibly the Huorns. However, unlike Ents or Huorns, he is portrayed more like a tree, with roots in the ground, and without the ability to move from place to place. Tom Bombadil had power over Old Man Willow, and checked the evil as much as he could, or was willing.