A new rare mob, a Krakken named Gaiju was datamined from the 6.1 PTR, along with an item called Gaiju Pearl, which transforms you into a Murloc with 200% swim speed. So far there is no information about where he spawns, and I haven't been able to find him, despite searching virtually the entire ocean of Draenor.
I tried asking a GM if he's actually in the game, but he flat out refused to say if Gaiju even exists or not.
Has anyone found him yet?