Lauren Conrad vs. Heidi Montag

Things turned sour for The Hills hotties when Montag started dating creepy Spencer Pratt in 2006. The feud came to a head when rumors of a nonexistent sex tape (featuring Conrad) hit the tabloids, with Pratt dubbed the likely culprit of the leak. A tear-soaked LC confronted Montag about her boyfriend's shady ways and ended the conversation with, "I want to forgive you... and forget you." Then Montag turned all sorts of crazy.