O'Dwyer is an Irish surname from the Gaelic ó Dubhuir, meaning "black". O'Dwyer in Irish is "O'Duibhir" (pronounced O Dweer), meaning grandson of Duibhir, an ancestor who, by tradition, lived sometime around the tenth century. The exact meaning of the ancestor's name is unknown, though 'black skirt' is one possibility, but the common modern consensus is that it means 'black and dun-coloured' which is thought to refer to Duibhir's hair coloring. Michael Dwyer (1771 - 1825) defied the English Government forces for five years, from 1798 to 1803, and was sentenced to transportation after his voluntary surrender. Today there are approximately 1500 bearers of the name O'Dwyer living in The United States.