Derived from the Old Norse byname Draki or the Old English byname Draca both meaning “dragon”, both via Latin from Greek δράκων (drakon) meaning “dragon, serpent”.
From the Irish Ó Dubhghaill, which means “descendant of Dubhghall”. A famous bearer was Sir Arthur Conan Doyle (1859-1930), the author of the Sherlock Holmes mystery stories.