3. Wolverine

Apart from the fact that he was born with claws, Wolverine had the same kind of treatment in order to make his bone structure much stronger. With a successful experiment done, this superhero not only becomes invincible, but also has a darker side. Well, Wolverine also has an exceptional healing power, which ensures that killing this superhero is out of the question. Yes, you could injure him and keep him out of action for a little while, but that is about it.