The Lord Protector of the Commonwealth of England, Scotland and Ireland was the title of the head of state during the Interregnum, following the first period of the Commonwealth under Council of State government. It was held by Oliver Cromwell (December 1653 – September 1658), leader of the roundheads and his son Richard Cromwell (September 1658 – May 1659) during what is now known as the Protectorate. 