Take a look at this video of the intro dialogue from Mortal Kombat X (skip forward to 15 seconds):That, in Quan Chi's hand, is the head of Moloch; an Oni (demon) of the 5th Plane of The NetherRealm. Moloch, along with his partner Drahmin (who is one of Ed Boon's least favorite characters and unlikely to be making a comeback anytime soon), were enlisted by Quan Chi to protect him from the continuous assaults of Scorpion; when Quan Chi and Scorpion escaped the Netherrealm through a portal they followed suit. Moloch and Drahmin were then enlisted by Shang Tsung as his insurance policy against Quan Chi betraying him during the events of Mortal Kombat: Deadly Alliance; once released from Shang Tsung's palace they ironically protected Quan Chi from Scorpion again and defeated him for the second time. Both were thought destroyed by Raiden's explosion at the end of that game but returned, alongside every character to appear in the franchise, in Mortal Kombat: Armageddon. The three-eyed demon is the tallest (standing at 16' 6") and one of the heaviest characters in the franchise. While some may point to the image in the video as an Easter egg or fan service; it seems like a lot of effort to go to just for that. Given the hints in Mortal Kombat 2011 about where the story for MK X might go; surely Moloch must appear. At the very least in a cut-scene or as a non-playable sub-boss or secret fight.