Nice Holystone (Baccano) is at least borderline disfigured. It's kept mostly hidden by hair, but it makes sense that she would do so.
Same can be said for D. Grayman's Klaud Nine
The only thing wrong with King (One Punch Man) is that he wouldn't have that scar in that location and still have a perfectly un-touched eye. They screwed up there.
That's actually the one problem with Balalaika's scar, but to a lesser degree. Unlike King, her eye is affected, but to me, not enough. She should have less perfect function of her eyelids. They are only slightly affected (they don't open symmetrically with the unscarred side), and that doesn't look right. They show no other functional trouble.
But yeah, all told, she might be one of the most realistically scarred characters in anime.
