Original: Rocky Marciano ( September 1 , 1923 -- August 31 , 1969 ) , born Rocco Francis Marchegiano , was the heavyweight champion of the world from 1952 to 1956 .
Simplified: Rocco Francis Marchegiano , better known as Rocky Marciano ( September 1 , 1923 -- August 31 , 1969 ) , was an American boxer .