Dryad

Dryads are wood nymphs in Greek mythology, and appear in various fantasy canons. They are also favorite species for Suethors, due to their legendary beauty. They are often described as being bound to a specific tree, and when that tree is hurt, they are also hurt. Sometimes, they are the spirit or soul of that tree, taking a humanoid form.

They appear canoncially in The Chronicles of Narnia, Dungeons and Dragons, Discworld, World of Warcraft, and various others.

They do NOT appear canoncially in Lord of the Rings. Ents may be a similar idea: tree people. But there are no dryads -- not even the fabled and lost Entwives were dryads.