Season 2: Kate, Locke & Sayid find the crazy Russian mercenary named Mikhail - he with the patch over his right eye. They fight, his house explodes, they take him as a prisoner.
Mikhail tries to explain something to Kate then says: "never mind you're not on the list." Current season: Kate is a candidate. Hmmmmm.
Mikhail explains that he was the last of the Dharma initiative. Why was he not killed by Ben & the Hostiles? Theory: Jacob touched him - making him immortal.
Then, Mikhail leads the party to the electric pylons outside the grounds/barracks around the Others. Locke throws him into the electrical force field - killing him. As he's being electrified, he says 'thank you.' Of course, Mikhail comes back later to kill Charlie.