In the initial plane crash, John Locke acquires a scar over his right eye.
Throughout the series, the scar heals somewhat, but it never fully goes away.
He still has it in his final appearance in The Life and Death of Jeremy Bentham.
When in Locke's form, the Man in Black also has the scar. Since he can only take the form of dead people, that means that Locke died with the scar.
However, the Island heals people. While it can't heal certain major things, it has been consistently shown to heal minor things like scratches and scars.
Since Locke spent significant time on the Island, why didn't his scar ever fully heal?






