War of the Ring
The Ents appear in "The Lord of the Rings" as ancient shepherds of the forest and allies of the free peoples of Middle-earth during the War of the Ring. The Ent who figures most prominently in the book is Treebeard, who (credibly) claims to be the oldest creature in Middle-earth. At the time of the War of the Ring, there are no young Ents (Entings) because the Entwives (female Ents) were lost. The Ents are akin to Huorns, whom Treebeard describes as a transitional form of trees which become animated or, conversely, as Ents who grow more "treelike" over time.