The Smoke Monster IS the MIB by Tara

So, forgive me if this has already been posted, I may be far off but, I think the smoke monster is the MIB. And here is why!

First I will say that the Smoke monster is the lingering spirit of Jacob's Enemy dressed in black,(MIB) as shown on the Season 5 Finale. Many times, it has been said they don't know what it is. But in the end of season 5 Ben tells locke he must be judged by it to see if he will be allowed to live or die.

Judging - It scans and judges you to see if you are on the good or bad, dark or light side. Meaning, that the MIB will be able to use you effectivly to continue his plan for the island. This is why John never gets killed by it or Ben. Instead when Ben was being Judged, it turned into Alex,(which was actual the MIB) and told him to do whatever John Locke Says. Ben will. So he let him live. I could go on and on about this with all the other characters, that have been killed etc... But I think you get the point as to where that is heading.

It Kills - It has killed! For example the people on the freighter. It killed a few of them, knowing that capturing Ben would only be good for the island, and not the MIB's plan. After all he needs Ben in the end game.

This is a a loop. The MIB and Jacob talked about it. so The smoke monster knows already whom he must kill and who must stay for the result to end his way.

So who has the smoke monster impersonated.
Yemi- And then Eko Dies from the smoke monster.
Alex - To Make Ben do as John Locke Says
John Locke - After his death and being brought back to the island to seek Jacob and kill him
Christan Shepard - To get John Locke to believe he is the new leader, to get him to leave the island in which will cause his death when he returns.
Claire - To Get Aaron off the Island to be raised by her Mother.

You get the picture, all events that will lead to the MIB to win his war on the island. This is why when people die in the first season i think they ship the bodies, out to sea, so that the spirits of the Island cannot take over the deceased bodies. This is also why Miles was hired to go to the island, cause they all believe that it is The ghosts of people from the past, and not the MIB. And also why the Smoke monster cannot go into the living quarters, that is sealed by the sonic fence. Ghosts, do not adapt well to the Sonic sounds (Thinking of the Ghostbusters ghost trap thing here)

So all in all, The MIB or Smoke Monster is sifting through as he has before, taking over bodies, and trying to find that loophole to actually kill Jacob and run the island in all that is evil.