Gavan Duffy is a compound surname. A list of people with the name include:
Charles Gavan Duffy (1816–1903), Irish and Australian editor, politician, and jurist
Frank Gavan Duffy (1852–1936), Australian jurist
George Gavan Duffy (1882–1951), Irish politician and jurist
Louise Gavan Duffy (1884–1969), Irish nationalist and Irish language enthusiast who founded an Irish language school
Charles Gavan Duffy (judge), a former judge of the Supreme Court of Victoria