Eric "The Eel" Moussambani
On September 19, 2000, Equatorial Guinea's Eric Moussambani instantly became one of the most famous Olympians for many years - but not for the reasons he might have hoped. Moussambani only made the Olympics thanks to the IOC relaxing the qualification standards for smaller nations, and due to the lack of facilities in his home country had never even trained in an Olympic size swimming pool before. But he got a stroke of luck in his 100 metres freestyle heat, when his only two opponents - from Niger and Tajikistan - both contrived to fall into the pool before the start, and were disqualified. That left Eric to swim alone, meaning all he had to do to win the heat was complete the race.
That was easier said than done. Moussambani belly-flopped into the pool and started swimming - slowly. He made one length of the pool, and turned, but then started to tire rapidly. As he wearily splashed his way back, getting slower with every stroke, the watching crowd were desperately cheering him on, while lifeguards were poised to rescue him if he started drowning. For a while it looked like he wouldn't make it, but inspired by the crowd, he finally managed to flap his way to the finish. He recorded a time of 1 minute 52.72 seconds - over a minute slower than the world record - but instantly became a media celebrity and folk hero for his efforts.
Unfortunately, despite winning his heat, he didn't qualify for the next round as his time was too slow.