This square-jawed character actor is best remembered not for his role in the TV series "Combat" (ABC, 1962-67), but for his first and last movie roles. His first--"The Blackboard Jungle" (1955)-- established him; his last--"The Twilight Zone-The Movie" (1983)--made him an industry martyr.The New York "method" actor was 23 when he was signed by MGM to play the toughest of the hoods in the high school drama "The Blackboard Jungle". His menacing performance led to a role in "Tribute to a Bad Man" (also 1955), but Morrow--at the tail-end of the studio system--had to settle for freelancing