William Patrick "Parry" O'Brien (January 28, 1932 – April 21, 2007) was an American shot put champion. He competed in four consecutive Summer Olympics where he won two gold medals (1952, 1956) and one silver medal (1960). In his last Olympic competition (1964) he placed fourth. For all of these accomplishments, O'Brien was inducted into the IAAF and U.S. Olympic halls of fame.