Paris Hilton vs. Nicole Richie — The Simple Life Breakup

Best friends since childhood, Paris and Nicole had a public falling-out in 2005 that ended their hit reality show The Simple Life — which was averaging 10 million viewers. Tabloids ran the story for months. The alleged cause: Nicole showed people a sex tape parody at a party. The show returned for two more seasons with the stars literally refusing to speak to each other, which somehow made it MORE entertaining. They eventually reconciled, and both went on to build empires. But the feud proved that reality TV doesn't need friendship to work — it needs tension. The ratings during the silent treatment were the show's highest.