Isiah Thomas
The Pistons faced the Celtics in the Eastern Conference Finals in 1987. Boston trailed by a single score with 10 seconds left on the clock. It appeared as though their luck had run out and that Detroit would claim a historic victory. But then Thomas made a career-defining error that cost his team the series (via USA Today Sports).
Larry Bird snatched an inbound pass from Thomas who should have tried to run down the clock. All he had to do was run down the clock but he failed miserably. Then Bird passed to Dennis Allen who sealed the victory for his franchise. The Pistons lost against the Lakers in the Finals but this was a day of ecstatic celebration.