Bartman isn't close. Not his fault they continued to choke. Plus he's a fan. He paid money to be there. Not the other way around. Most people would probably do the same thing.
My nominee: Tom Osborne in the 1983's Orange Bowl/NC game Nebraska vs. Miami
All he has to do is kick an XP to tie the game, which win the national title for Nebraska.
Instead he goes for 2, fails, loses 31-30 and Miami wins the NC.
Oklahoma v. Oregon 2006
Not only was the ball touched by Oregon before 10 yds, but #23 for Oklahoma recovers the ball at the right of the screen. Had the call been correct, even after review, Oklahoma would have killed the clock and won. Erase that loss and I think they end up in the BCSCG that season.
That said, F the Sooners!
you play to win the game