agitator

1647, from agitation (q.v.), originally "elected representatives of the common soldiers in Cromwell's army," who brought grievances (chiefly over lack of pay) to their officers and Parliament. Political sense is first recorded 1734, and negative overtones began with its association with Irish patriots such as Daniel O'Connell (1775-1847). In Amer.Eng., usually with outside and referring to people who stir up a supposedly contented class or race.