Demagogue

Demagogue (Gr. δημαγωγός, from ἄγειν, to lead, and δῆμος, the people), a leader of the popular as opposed to any other party. Being particularly used with an invidious sense of a mob leader or orator, one who for his own political ends panders to the passions and prejudices of the people, the word has come to mean an unprincipled agitator.