Salvatore `` Sal '' Mineo , Jr. ( January 10 , 1939February 12 , 1976 ) , was an American film and theatre actor , best known for his performance as John `` Plato '' Crawford opposite James Dean in the film `` Rebel Without a Cause '' .
Salvatore `` Sal '' Mineo , Jr. ( January 10 , 1939 -- February 12 , 1976 ) , was an American movie and theatre actor . Mineo was best known for his performance as John `` Plato '' Crawford opposite James Dean in the movie `` Rebel Without a Cause '' .