Today is Keith Hernandez's 57th birthday. Some remember him as one of the best first basemen of his era. Other may recognize his work as a Mets analyst for Sportsnet New York. But let's be honest: Hernandez will always be known for his appearance on Seinfeld, which may go down as the greatest performance by an athlete on a sitcom in television history (or a close second to Kevin McHale on Cheers). In honor of Hernandez's big day, Complex has put together its list of the best athlete cameos on TV shows.