Michael

Michael & Walt also escaped the island.
Are they included in the Oceanic Six?

That would explain Kate's disgust to Jacks questioning whether or not she attended 'the funeral'. It would have been Michael. Kate didn't like Michael, since she was on his "list" of people to kidnap & bring to the others. He betrayed his friends, killed libby & ana-lucia, kidnapped his four friends & brought them to the others and freed Ben.

I think Micheal is also Ben's spy on the ship.

I don't remember where I heard it, but I *think* I heard that Michael was coming back to the show.