J.R.R. Tolkien called the great tree-like people in The Lord of the Rings Ents.
The Ents are ancient shepherds of trees who live in Fangorn Forest. Their best-known leader is Treebeard, whose name in Tolkien’s invented language Sindarin is Fangorn. Merry and Pippin encounter him after fleeing from the Orcs, and their meeting helps awaken the Ents to the damage Saruman’s forces are causing to the forest.
The Ents eventually march on Isengard in the Entish attack known as the March of the Ents. They destroy much of Saruman’s stronghold and help end his power in the region. Their slow deliberation contrasts with the urgency of the War of the Ring, but their action becomes strategically important.
Huorns are related, more mysterious tree-like beings, but they are not the general name for Tolkien’s speaking tree shepherds. The Eagles are giant birds, and the Maiar are a separate order of spiritual beings.