Frank Byrne (1848–1894) was an instigator of the Irish National Invincibles, the radical offshoot of the Irish Republican Brotherhood.
He was implicated, if not as the organiser, then at least as the spirit behind the assassinations of Lord Frederick Cavendish and Under Secretary Thomas Henry Burke in the Phoenix Park murders of 6 May 1882.
He was one of only two who managed to flee Ireland to escape prosecution for the crime.
His escape was the source of much legal wrangling in Ireland, France, and the United States.