What is it called when someone uses people?

From my knowledge, the answer to this question is a 'manipulator'. Hopefully that helps with an answer.

Uggghh..I've been looking for this as well...The only Word I can think of is blackmailer...

I would like to propose that a new Word is used for such an act. I would like to give the Word 'exploitationist' for such a thing as using others or things to the advantage of themselves.