John Pym was a politician and administrator from London, who played a major role in establishing what would become the modern English Parliamentary system. One of the Five Members whose attempted arrest in January 1642 was a major step in sparking the First English Civil War, his use of procedure to out manoeuvre opponents was unusual for the period. Though this meant he was respected by contemporaries rather than admired, in 1895 historian Goldwin Smith described him as "the greatest member of Parliament that ever lived".

The Five Members were Members of Parliament whom King Charles I attempted to arrest on 4 January 1642. King Charles I entered the English House of Commons, accompanied by armed soldiers, during a sitting of the Long Parliament, although the Five Members were no longer in the House at the time. The Five Members were:John Hampden Arthur Haselrig (1601–1661) Denzil Holles (1599–1680) John Pym (1584–1643) William Strode (1598–1645)