James MacArthur, famous for his role as Danno on the original Hawaii 5-0, has died at the age of 72 on Thursday.  His agent reported that he died of natural causes but no official report on the cause of death has been released.  Hawaii 5-0 originally aired from 1968 to 1980, and MacArthur was on every show until the last season.  He left 5-0's cast before the start of the last season, stating that the show had become boring and repetitive, and no longer challenged him as an actor.  Born on December 8, 1937, he was the adopted son of playwright Charles MacArthur and movie star Helen Hayes.  Silent film star Lillian Gish was his godmother.