Neutral evil is pure pragmatism without honour and without variation—survival of the ruthless. In 4th edition mechanics for Dungeons & Dragons neutral evil is found under the umbrella of the evil alignment.
A neutral evil character does whatever he can get away with. He is out for himself, pure and simple. He shows no remorse for those he kills, whether for profit, sport or convenience, and he has no love of order and holds no illusion that following laws, traditions, or codes would make him any better or more noble. On the other hand, he does not have the restless nature or love of conflict that a chaotic evil villain has.
Some neutral evil villains hold up evil as an ideal, committing evil for its own sake. Most often, such villains are devoted to evil deities or secret societies.
Sephiroph is a good example of Neutral Evil