Actor James MacArthur, best known for his role as Jack Lord’s sidekick Danny on the long-running TV series Hawaii 5-0, has died at the age of 72. MacArthur, the son of playwright Charles MacArthur (The Front Page) and adopted son of actress Helen Hayes, had a forty-year acting career that included a great deal of work in films and stage, including a number of live-action films for Walt Disney. But his greatest success was on television, where his supporting role on Hawaii 5-0 gave him eleven years of employment (he left the show before its final season). His character was best known for being the recipient of Lord’s catchphrase “Book ’em, Danno.” MacArthur was reportedly considering a guest appearance on the current remake of Hawaii 5-0 before he died.