“Roundhead” was the name given to the supporters of the Parliament during the English Civil War. Also known as Parliamentarians, they fought against King Charles I and his supporters, the Cavaliers (Royalists), who claimed absolute power and the divine right of kings.
The goal of the Roundhead party was to give the Parliament supreme control over executive administration. Most Roundheads appear to have sought a constitutional monarchy, in place of the absolutist monarchy sought by Charles I. However, at the end of the Civil War in 1649, public antipathy towards the king was high enough to allow republican Roundhead leaders such as Oliver Cromwell to abolish the monarchy completely and establish the republican Commonwealth
- Wikipedia for background