Leicester City, 5000-to-1 (2016)
In August 2015, you could get 5000/1 on Leicester City winning the Premier League. Bookmakers called it a novelty price — the same odds they offered on Elvis being found alive.
Leicester had nearly been relegated the season before. Then they lost three league games all year and won the title by ten points. Books reportedly paid out over £20 million combined, and several paid out early to punters who had taken the joke price seriously.
Buster Douglas knocks out Mike Tyson, 42-to-1 (1990)
Mike Tyson was 37–0 and considered unbeatable when he met James "Buster" Douglas in Tokyo. Douglas was a 42-to-1 underdog — one of the biggest prices ever offered on a heavyweight title fight.
Douglas knocked Tyson out in the tenth round. It remains the standard every heavyweight upset is measured against.
UMBC over Virginia, a 16-seed wins (2018)
No 16-seed had ever beaten a 1-seed in the men's NCAA tournament. Then UMBC didn't just beat Virginia — they beat them by 20 points, 74–54.
Moneyline prices around +2000 turned small stakes into enormous payouts, and every future 16-seed has been priced with that night in mind.
Greece wins Euro 2004, 150-to-1
Greece had never won a match at a major tournament. They were 150/1 outsiders before Euro 2004 — and then they beat the hosts Portugal in the opener, and beat them again in the final.
Otto Rehhagel's team conceded four goals in six games. Defence doesn't sell shirts, but it cashed one of the great underdog tickets in football history.
Miracle on Ice (1980)
A team of American college players against the Soviet Union — winners of nearly every major international tournament for two decades — at the Lake Placid Olympics.
The US won 4–3, then beat Finland for gold. There was barely a betting market to speak of; the upset was pure sporting mythology. Some nights the number doesn't matter.
The lesson the books already know
Longshots lose far more often than they win — that is why the prices are long. But the board is a price, not a prophecy, and every one of these nights started with a number the market was happy to offer.
A note on the numbers
Historical odds are reported from contemporary coverage. Current prices change by the minute and differ between books. Nothing here is a betting recommendation.