User blog comment:Bluefox87/Chapter 416 Natsu is E.N.D...WHAT?!?/@comment-72.80.142.77-20150120204201/@comment-9595671-20150124101826

We only know Warrod is a former/retired Fairy Tail member who's #4 of the top four wizard saints and somehow now looks like a tree.

The last 3 we lack any info on, we can probably assume like Warrod they aren't human (or atleast as human) like the other 6