Give some stream of consciousness and then the answer. 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 in the long-running television series Hawaii Five-O.

Answer this question: who played dano on the original hawaii five-0?
The important part for answering this question is: 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 in the long-running television series Hawaii Five-O.
Therefore, the answer is James Gordon MacArthur.