MiB's name is...

[doubleohfive]

Better answer: Milo Rambaldi.

 

[Hober Mallow]

I think the reason they didn't give MIB a name was that they couldn't come up with a name cooler than Titus Welliver's actual name.

I guess the writers thought it would be cool to not give him a name. I thought it was silly that they didn't reveal his name in Across the Sea. The main characters ended up calling him Locke during the last couple of episodes.

At least they didn't insult our intelligence by having his mother and Jacob also inexplicably call him Locke.

Jin being the Kwon candidate is also supported by the fact that he wasn't killed when the freighter went kablooey in the season four finale.

I also assumed that was why Sun didn't travel back in time with Jin and the other candidates.