A person who uses others for his or her own personal gain and abruptly ends the "relationship" when the person is of no further use to them. This person is often physically or emotionally draining to be around and seems to become more energetic as others become drained.
Jason: I don't understand why Lauren won't call me back anymore to hang out.
Willis: She doesn't need you to drive her places now.
Jason: I thought we were still friends.
Willis: She's a narcissistic cannibal, she doesn't make real friends. She just uses them up.