1) Similar to a homewrecker, only this person comes in and ruins groups of friends to obtain certain members of the group to their own loyalties.
2) A member of a crew who lies, steals or talks shit about the crew in order to cause discord so that a few people will leave the crew.
Jane:"Man, we were all good until James met Sarah."
Josh:"Yeah, since then all Sarah has done is spread rumors about everyone."
Jeremy: "Can't ya'll see, she just wants James all to herself. She is a crewrecker."