Board Thread:Mortal Kombat X/@comment-1084762-20150401222951

With the obvious decoy random char button, there's no doubt in my mind that the last character is sitting behind it (and IIRC, they did they you could unlock someone from beating story). After all, in early showings of MK9 there was a random select button slot which would later become Cyber Sub Zero's. Anyways, I just don't know who it could be. Fujin, maybe, since he seems somewhat important. Maybe another out-there, crazy what-if char like CSZ again.

Another thing to consider is that Goro's slot on the roster could easily be a placeholder too, so there's a possibility of 2 secret characters. 