If it is indeed obvious, Shinnok is the only one. Mileena battle vs. Kotal is early on so my bet is she will be playable. Also, while she is more powerful, I cannot see her as a boss.

The only guys who could potentially be the boss are who NRS has been surprisingly quiet about: Liu Kang & Shang Tsung. I also like the idea of Evil / Dark Raiden.

To all those saying Reiko, Daegon and Onaga: let it go. Daegon was a throw in character, appeared in one game, you really think they would use him as a boss? NRS is not that stupid. Same goes for Onaga, he would be surprising and returning, but nothing hinted at him + he's just a big buffoon with wings. Lastly, Reiko. He could be playable since he appears in the comics, but with Shinnok being in and Mileena being very important to the story, it would be very idiotic if Reiko is somehow pulling the strings.

Shang Tsung: for a boss in MK1, being in almost every game, a big role in MK9 and no word on him yet is surprising in itself. Why he could be the boss? He was always plotting and scheming, could be hiding in the dark, form an alliance with Quan Chi again and try to get a hold of the amulet. Then absorb Shinnok's power and be a powerful bad ass he always wanted to be since he always served Shao Kahn.

Another reason why he could be is because his soul being absorbed by Mileena in her MK9 ending. With her being more powerful and survival, this could suggest she already has his powers. Knowing Shang Tsung, he could easily use souls for his own gain, thus releasing himself from Mileena's body whenever he sees fit. It could be that Mileena is the sub-boss and when beating her, Shang Tsung reveals himself and uses the amulet's power again to be a demon or blood god or whatever.

Liu Kang: his CANON ending in story mode of MK9, his own ending where he becomes a god, the red smoke from the Shaolin temple and his absence so far works in his favour. The fact it, he's dead at this point and with the new good guys, Cage being champion, his role as #1 protagonist are over. With the turn against Raiden, his story could be very well intertwined with what is happening. It relies heavily on speculation like with Shang Tsung though:

Liu's story ending is him defeating Raiden and becoming the protector of earth realm, but as the thunder god. His eyes and hands screamed fire god and it would make sense, but the story stated thunder god. Since Raiden is clearly still the protector of earth realm and thunder god, this story ending holds little ground.

His CANON ending though could lead up to him becoming a god though. Liu Kang could be revived by any number of people: Quan Chi, Tsung, Raiden, Fujin, Bo Rai Cho even. What if he insisted on revenge and tries to find a way to do this? Here is where the amulet and the blood demon come in. Combine this with someone or something escaping the Shaolin temple, it could be Liu Kang unleashing these powers for his own gain?

To me, while this would count as a surprise returning character, especially because he was dead in CANON and has not been mentioned at all, the story is too much about revenge. I cannot picture Liu Kang becoming fully evil and try to take over the realms. This would also not suit his personality. He could try to be the sole living god and go after Shinnok as well as Raiden, but that is too far fetched.

Another option could be that Liu Kang is revived and tries to fight Raiden, as he does in his story ending, but ends up losing. Raiden then uses the amulet to trap Liu to contain him as well as Shinnok. I don't know how the amulet works, but since Shinnok is claimed in the comics to be imprisoned again. What if he is imprisoned by the elder gods, so cannot escape the amulet, but Liu Kang can thus Raiden fears Liu Kang (the story mode scene where he says he fears the talisman)?

Dark / Evil Raiden: I would love this, but since Raiden has been revealed already, it would be weird. You would get two Raiden's, but let's explore it anyway.

In the comics, we're at the point where Raiden tries to fight Scorpion, has been cut by the dagger and is evil. It is possible that Raiden fears the amulet because he knows that when the 'force or powers' escape, everybody will be affected, including him (the last good god). The red smoke could be that power, turning Sindel and Kitana into evil. Raiden is a god, so for him to be turned evil and maybe possessed by a demon god, an even greater power could be unleashed.

Dark Raiden has appeared in the game before, so while two Raiden's is probably not going to happen, I would love the idea of a dark force using Raiden's god status to finally destroy him, claim earthrealm and destroying the good forces in the process. Unlikely, but it would be surprising haha.

I think Havik is involved in someway shape or form now, coming to think of it. If it falls within his hands, he can pretty much do whatever.

Havik is another option you should just let go. They even joked about him during the stream, as well as Sheeva so he's probably not even in. Havik wants chaos, nothing more, so means very little to the story they have put forward so far. I like Havik's potential, but his fighting style was lame as shit and his appearance in MK9 was very little in which he returned to chaostealm because order had been restored.

The Liu Kang theory is an interesting one. One of the most interesting differences in the plot of MK9 compared to the traditional MK story was that Raiden kills Liu Kang. At the time I thought it was completely random and unnecessary. However, it could very well be leading up to something big.

The absense of Shang Tsung is interesting as well. All other characters from MK1 besides Liu Kang and Shang Tsung have been pretty much confirmed. It would make sense for the whole cast of MK1 to be featured in the game somehow. Up until now, I just thought they excluded Shang Tsung because of his prominent role in the last game and the fact that most people don't see him as "big bad" status. Being a big fan of his, I would love for it to be him. But I just don't see him as more powerful than Quan Chi or Shinnok. Perhaps Shang Tsung is disguised as another character, such as Reiko or Ermac, and is secretly plotting to overtake the throne. It's possible.

If Havik doesn't make this game, then he's in MKXI for sure.

What do people have against playable bosses?

Blech. Though it's unlikely, I sincerely hope that's not the case.

Nothing would suck the heat from those two guys faster.

takes away from them seeming overpowered, since they get balanced for normal fighting.

Agreed 100%.

I'm beginning to think we'll fight Shinnok at the end of the first act. Then we'll fight him again as the big bad, but way more powerful. His new design is just way too epic.

Another theory: Raiden does not fear Shinnok (he trapped him before ;), but the form he could take, that of a dragon. As you may know, the elder gods appear as dragons:

Additionally, the Elder Gods are said to appear as dragons in their true forms. The dragons resemble those seen on the Mortal Kombat dragon symbol, and that is likely why the symbol is so prevalent throughout the series. Images of the Elder Gods as dragons can be seen in Onaga's unused Deception ending, the archway of a temple in Armageddon's Konquest mode, Captain Marvel's Mortal Kombat vs. DC Universe ending, and the climax of Mortal Kombat (2011)'s Story Mode.

http://mortalkombat.wikia.com/wiki/Elder_Gods?file=Onaga%27s%20Ending%20Deception.PNG

Could the red smoke cloud be Shinnok in the form of a red dragon?

I would love the idea of fighting Shinnok as boss who after defeated turns into a red dragon who you consequently have to beat and is the big bad!!

Shinnok turning into a dragon would at least be interesting and surprising. Him simply returning at the end as the boss would not be interesting or surprising. I do agree with the theory that there could be three bosses, which one boss per chapter. Shinnok could be the first one, Kotal Kahn for the second, and whoever the big bad is for the third, who in my opinion will be none other than Reiko. But in order for the Reiko theory to work he would have to be working together with Quan Chi and Shinnok in some kind of a plan to take over all the realms.

If Shinnok turns into anything I'll bet it'll be that big ass monster he was in Mythologies.

I think the final villain's either Shinnok or someone unexpected, like a non-teamed up Shang Tsung as the main villain, or Mileena given a big push. I'm still rolling with Shinnok for the time being.

Then again they said it would be obvious from the trailer. I'm gonna say it's Shinnok, and if not, then it's Mileena given a boost.

As for Liu Kang's death, the only thing I think that's leading up to is Liu coming back as a hero again, but he'll be reluctant to work with Raiden. They'll have to team up to take out the final villain and earn eachother's friendship once more and come to an understanding. Maybe Raiden will pass title of Protector onto Liu.

Ooh wow, lets wait another 4 to 5 years then.

My guess is it's actually Goro.

You see him get smashing in the comics (i know he didn't die, but still) and every trailer for the game ends with "Goro Lives". Seeming to be quite healthy if it it indeed after the comics.

Just my 2 cents.

Did you realize that this quote of Ed Boon "the big bad is going to be a surprising returning character" was waaaaayyyyyy months ago?

Months ago we didn't even know about Mileena. Not even the comics came out.
So my money is on Mileena for sure. And to be honest, if shes got some IQ this time, she's a badass main boss.

All these leaks and we still dont know who the final boss is.

All the leaks were about obvious characters.....

Hmmmm

Am I the only one that notice that Raiden doesn't even seem to remember imprisoning Shinnok. The way he talked about the amulet with the group, it was like he didn't even act like he ever had it or beat Shinnok with it....that plus that outfit he was wearing.....something about Raiden in this one seems off lol.

LOL what are you smoking? He's actually acknowledging that if it is the talisman he used to imprison Shinnok, they will all be in big trouble. How did he forget?

What is interesting is what happens to Raiden when takes Shinnok into the talisman, as if a force is going inside of him. This could allude to an evil Raiden, which could explain the red smoke coming from his temple. However, could just be the shock of the energy that is going inside of the amulet.

Some people are thinking about a blood demon, but when was that ever a character?

I'm still wondering why NRS killed Shang Tsung to give his power to Sindel? they probably wouldn't do that to finally kill Sindel too, just a theory.

What if (the devil) Sindel claims the throne too as Impress, she could be the boss finally. Plus NRS said that they would hint the boss in the story trailer ( im not sure),

If it is the case, who would rally Sindel against Kotal and Mileena? Dragon king? Shinnok? the centaurian (nah)? someone else?

It'll probably be Reiko. I'm calling it now.

Why Reiko?

In MKMSZ Shinnok did have a larger demon form, so fighting him in base, then fighting him in a larger more powerful form doesn't seem that farfetched, its actually what I thought would happen originally before the boss was stated to be a fun returning character nobody would see coming.

i think it's either gonna be Shinnok, or Fire God Liu Kang

if it's neither of those then i will be SHOCKED!

I'm also gonna go ahead and call Reiko the big bad. It seems more and more obvious by the subtle hints they have dropped in the comics about him serving alongside Kotal as a general in Shao Kahn's army and about him being the mastermind behind Mileena's rebel faction. I know many of you can't picture him being the big bad but you aren't thinking about how Reiko may have the support of the Netherrrealm. Big bads can be like Shang Tsung in MK1, who aren't the biggest threat in the MK universe yet still are the driving point in the plot. Just as Shang served Shao Kahn, Reiko could be serving Shinnok, who might be freed near the end of the game.

I for one would welcome Reiko as the big bad. He is one of those characters with untapped potential. I could see him on the level of Shang Tsung or Quan Chi in terms of sheer evil. It would also be one of those cases were NRS could tie together some loose ends by making sense of Reiko's mysterious MK4 ending. Just like how they created a character out of Ermac. Going with the flow. It's a great way to create more depth and intricacy in the MK mythology. I also think Ermac is going to be making some moves in an attempt to bring back Shao Kahn.

No, Reiko has been far from hinted at and is just a Shao Kahn wannabe with make up on. Would be a failure as a boss and 99% sure he is not the big bad.