The Shepherds of the Trees
Ents or the Onodrim as they are called in Sindarin are described a race of tree-like giants that appeared in Middle-earth at the same time as the Elves. They were created as the Tree Herders to protect the trees from the other races (originally Dwarves) who aimed to cause them harm. They often resemble trees or plant-life, and it's been said that their appearances vary tremendously, according to the specific trees that they shepherd. Ents have been known to rise to anger when a fellow is killed.
In Skill Use
Huorns are a variation of Ents that are more tree-like and less sentient. It is said that they learned from the Ents, but are nothing more than "walking trees". Most are good, fighting on the side of the Ents to protect the forests, but a sect of Huorns known as Black Huorns are pure evil.