O'Malley (Irish: Ó Máille [oː ˈmˠaːl̠ʲə]) is an Irish surname. According to historian C. Thomas Cairney, the O'Malleys were the chiefly family of the Partraige who were a tribe of the Erainn, the second wave of Celts to settle in Ireland between about 500 and 100 BC.[1]