Biografía: ​From Wikipedia, the free encyclopedia.   James Gordon MacArthur (December 8, 1937 – October 28, 2010) was an American actor best known for the role of Danny "Danno" Williams, the reliable second-in-command of the fictional Hawaiian State Police squad Hawaii Five-O. Description above from the Wikipedia article James MacArthur,  licensed under CC-BY-SA, full list of contributors on Wikipedia.