Bullies.

People tend to have the wrong perspective on bullies. The classic line that parents tell their kids when they someone once called them a name. "Do not listen to him, he just thinks poorly of himself so hes putting you down". Apparently that is false. Most bullies actually have a high self esteem. As a researcher of this topic Jaana Juvonen says "they are viewed by their fellow students and even by teachers not as pariahs but as popular — in fact, as some of the coolest kids at school."  People get confused as to how bullies can be the popular kids. Bullies are thought of as mean, quite kids who think up of evil plans from the side lines. But that vision is false.
 Bullying also is a big part of developmental psychology. You hardly ever see bullies in younger grades but you often see many starting in 6th grade. This has to do with the crazy development that takes place during that age. They change from being in elementary school to being in a larger school often. Many students start hitting puberty. People begin to give them more responsibilities.  There are changes at school, changes a home and changes within themselves."Floundering and frightened, not knowing where they fit in "probably calls forth a primal tendency to rely on dominance behaviors," Juvonen suggested. The bigger, stronger kids create a social hierarchy and appoint themselves the leaders. The bullies are clearly in charge, gaining power and status that translate to a bigtime ego boost." 
Bullying is something that is mean and can often lead to bad things. In a strange way there is nothing we can do about it though. Most bullies will be bullies no matter what. It is sad but hopefully if we spread awareness and make the transition for pre teens easier there will be less bullies and less victims.