Kim Perrot is my choice right now, but some of these careers are still in progress. Starting point guard on several championship teams at the highest level of her sport. Just looking at the number of prospective athletes and very small number of teams and starting roles in the WNBA, it takes a small miracle just to make a roster. To be a starter, you have to be elite. To be a starting point guard on a WNBA championship team several years in a row, you have to be Kim Perrot, because I don't think anyone else has done it.
Jake gets my honorable mention. The number of QBs that have led their team to the Super Bowl is also some improbable fraction when compared to the number of prospectives.