Treebeard is the leader of the Ents in J.R.R. Tolkien’s The Lord of the Rings.
Treebeard, whose Sindarin name is Fangorn, is an ancient tree-like being who lives in Fangorn Forest. Merry and Pippin meet him after being captured by Orcs and entering the forest. He initially hesitates to involve the Ents in the conflict because he considers most affairs of the speaking peoples too hurried and complicated.
The Hobbits persuade him to hear their account of Saruman’s destruction of the trees around Isengard. Treebeard then calls the Entmoot, a gathering of Ents, and the Ents decide to march against Saruman. Their attack destroys much of Isengard and demonstrates that the natural world can become a decisive force in the war.
Quickbeam is another named Ent, while Old Man Willow is a different tree-like figure in the Old Forest. Tom Bombadil is not an Ent. These characters are often grouped together because Tolkien gives each an ancient connection to nature.