Look at teenagers - junior eligible players, who played in the NHL. Not a "best of" thread but more of a historic overview taking into account era, position, context, eligibility - Denis Potvin was never eligible according to the rules of the day to play in the NHL as a junior. First junior that comes to mind that continued on to a successful career was Harvey "Busher" Jackson. Others like Bobby Boucher were less fortunate. Goalies cover a wide range from Harry Lumley to Tom Barrasso and beyond. Defencemen from Fern Flaman to Larry Hillman to Bobby Orr to Drew Doughty. While forwards are too numerous to mention. There is the obvious drawback of physical and mental maturity. A teenager simply is not strong enough to play with men, so very often there is a sharp increase in performance once the player reaches physical maturity in the early twenties - evidenced by the sharp upward spikes in production from Gordie Howe, Bobby Hull, Bobby Orr, Wayne Gretzky, Mario Lemieux and others. Mentality the grind of a much longer season from junior to the NHL also takes a toll. Comments appreciated.