Oliver Cromwell

Oliver Cromwell (1599-1658) was an English military and political leader best known for his involvement in making England into a republican Commonwealth and for his later role as Lord Protector of England, Scotland, and Ireland. He was one of the commanders of the New Model Army which defeated the royalists in the English Civil War. After the execution of King Charles I in 1649, Cromwell dominated the short-lived Commonwealth of England, conquered Ireland and Scotland, and ruled as Lord Protector from 1653 until his death in 1658 from (presumably) septicaemia.

Oliver Cromwell in The Two Georges
As a regicide, Oliver Cromwell was a hero to the Sons of Liberty, the separatist organization that sought the independence of the North American Union from the British Empire. The more violent members of the SoL shaved their heads and called themselves "Roundheads", a nod to Cromwell's followers.