I remembered one more: Richard Alpert. I suppose there's more to come on this guy, but again- I felt the mystery of the guy was really... mysterious. Not only did he not age, but he seemed to be omniscient and omnipotent as well! He knew John Locke would come to the island 30 years before it happened! He made Juliette's ex get hit by a bus!

Turns out he was acting on information from a time traveling John Locke. Yeah, it makes sense and it gives us the very cool pocket watch loop... but it's kind of a lame handling of Alpert. He's just not as cool as he used to be. Throughout most of season 5, he seemed like he was kind of stupid.

Hopefully he gets some back in season 6.