Treebeard is the oldest Ent in J.R.R. Tolkien’s The Lord of the Rings.
Treebeard, whose Sindarin name is Fangorn, is the ancient shepherd of trees whom Merry and Pippin meet in Fangorn Forest. He is described as extremely old, and the forest itself bears his name in the Common Speech used by many characters.
After hearing about Saruman’s destruction of trees around Isengard, Treebeard calls the Entmoot, a deliberative gathering of Ents. The Ents eventually march against Isengard and help defeat Saruman’s forces there.
Quickbeam is another named Ent, while Old Man Willow is a powerful tree in the Old Forest rather than an Ent. Tom Bombadil is an entirely different mysterious being. These distinctions matter because Tolkien’s stories contain several ancient tree-associated characters.