User blog comment:Maki Kuronami/Lesson 27: Screw everything, have a Samurai!/@comment-4010415-20141024045439/@comment-25091485-20141024103227

It's probably some sort of lizard / dinosaur -ish Grimm :P It's kinda small compared to the Taiju that makes the Deathstalkers look like toys.

The final boss will probably be Cinder & Co. though, we haven't actually covered their end of the evil plan. Plus, Cinder & Co. has yet to fight RWBY (though its in the opening)