Elizabeth Waller was born in Castleton, County Limerick, one of the four daughters of Elizabeth Dowdall (died 1658) and Sir Hardress Waller (–1666).Her father was one of the regicides who condemned Charles I to death. After the Restoration of Charles II he was in his turn sentenced to death after being found guilty of regicide, but he was reprieved, and died in prison. Her mother was noted for her spirited defense of the family home, Kilfinny Castle, during the Irish Rebellion of 1641.