We'd like to believe that all of our favorite celebrities are beyond petty beefs. After all, they are rich and famous, and therefore our betters. So the squabbling that goes on every day for peasants like you and me shouldn't affect Hollywood stars. But fame and fortune can't change human nature, and it sure hasn't with the celebs on this list. So while some of these stars may have started out as friends, they went all high school and turned into celebrities who hate each other.