Treant 

These for all apearences are living tress.   In fact they are sentient pieces broken from the First Tree.

Elves view these as sacred beings and touchstones to their birthright.

With the departure of the elves, and the first tree removed from time, many of these Treants have not remained emotionally stable.  They can lash out angrily, sulk from loniliness, or are just so happy for company that they loath to let any living creature out of their sight.