Leonard Freeman (born October 31,1920, died January 20, 1974 ) was an American television writer and producer whose most famous achievement was the creation of the CBS television network series Hawaii Five-O in 1968.The show ran for twelve seasons . At the time that was a record for a crime drama . In 1960, he wrote for the series Route 66 ; in 1962, he produced The Untouchables . In 1967, he produced the Clint Eastwood western film, Hang 'Em High. Freeman died in 1974 during the 6th season of Hawaii Five-O due to complications from heart surgery.