Lauren Conrad and Heidi Montag
Lauren Conrad and Heidi Montag were a blonde, bubbly match made in heaven when they starred on The Hills together in 2006, but things quickly went sour once Heidi fell in love with Spencer Pratt. Lauren repeatedly tried to warn her friend about the bad boy, calling him "shady," but Heidi couldn't be bothered — she eventually chose her boyfriend over her BFF, and the friendship fell apart.
Cut to 2007, and Lauren runs into Heidi and Spencer at an LA party and confronts her former friend on air, saying, "You're a bad person." While LC reluctantly attended Spencer and Heidi's (televised) wedding two years later, she has revealed that the two "don't talk" anymore.