Wayne Gretzky is one of the most decorated athletes in sports history. Back on this day in 1984, with the Edmonton Oilers, he became the first teenager to score 50 goals in a season. This would be the beginning of an illustrious career that would see “The Great One” end up with the most points in NHL history, along with a slew of other accolades and records. Gretzky dominated his sport like few others have in history, but that’s not to say there haven’t been a host of baby-faced assassins that have dominated their respective athletic arenas. So, from LeBron James winning Rookie of the Year at 19, to Pele winning the World Cup at 17, we present The 20 Greatest Teenagers in Sports History.