Who: Pat Robertson, who in a 1980 broadcast of "The 700 Club" said "I guarantee you by the end of 1982 there is going to be a judgment on the world."
How he came by that date: Robertson has said that God told him about pending disasters on numerous occasions (including a West Coast tsunami in 2006, and a terrorist attack in 2007 – neither occurred). "I have a relatively good track record,” he has said. “Sometimes I miss.”
What actually happened: The world didn't end in 1982, but "WKRP in Cincinnati," did.