Greg dove in the 1976 Olympics and won silver on the 10m platform, and then that rockin' boycott happened in 1980 and prevented him, the gold medal favorite in two events, from competing. Cool, guys. He won world championships in 1982 in two events and then destroyed the 1984 Olympics, sweeping both diving gold medals. At worlds in 1986, he repeated his double gold performance of four years previous. And then, at the 1988 Olympics, he swept the golds again, becoming only the second diver in history to win each event in two consecutive Games.
However, what Greg is probably best known for is a screw-up (and the aftermath). At the 1988 Olympics, he hit his head on the springboard during the preliminary rounds and ended up with a concussion and a pretty nice gash. But he got stitched up real quick and walked it off, and on his next dive got the single highest score of qualifying. He repeated the dive he botched during the finals, and ended up winning gold by 25 points. With. A. Concussion.
And his Twitter bio? "If you're looking for the guy who hit his head on the diving springboard in the 1988 Olympics, you found him." YES.
He also happens to kind of be the best diver ever, with an Olympic career spanning 12 years. Americans really haven't been that great at diving since.
He also is HIV positive and openly gay, and an advocate for both. And despite Russia's anti-gay policy, he is resolutely against the prospect of a U.S. boycott because he himself suffered through one and he knows that it isn't the way to win.
And, again, he's a Cane. That's really all the reason you should need. ;)