I like the idea of Treebeard being an INTP.
'Saruman is a Wizard,' answered Treebeard. '[...] I told him many things that he would never have found out by himself; but he never repaid me in like kind. I cannot remember that he ever told me anything. And he got more and more like that; his face, as I remember it - I have not seen it for many a day - became like windows in a stone wall: windows with shutters inside. [...] Curse him, root and branch! Many of those trees were my friends, creatures I had known from nut and acorn; many had voices of their own that are lost for ever now. And there are waste of stump and bramble where once there were singing groves. I have been idle. I have let things slip. It must stop!Things have changed. [...] Some of us are still true Ents, and lively enough in our fashion, but many are growing sleepy, going tree-ish, as you might say. Most of the trees are just trees, of course; but many are half awake. Some are quite wide awake, and a few are, well, ah, well getting Entish. That is going on all the time. When that happens to a tree, you find that some have bad hearts. [...] Still, we do what we can. We keep off strangers and the foolhardy; and we train and we teach, we walk and we weed.