A demagogue or rabble-rouser is a political leader in a democracy who appeals to the emotions, fears, prejudices, and ignorance of the less-educated citizens in order to gain power and promote political motives. Demagogues usually oppose deliberation and advocate immediate, violent action to address a national crisis; they accuse moderate and thoughtful opponents of weakness. Demagogues have appeared in democracies since ancient Athens. They exploit a fundamental weakness in majoritarian democracy: because power is held by the most numerous group of people, one who appeals to the lowest common denominator attitudes of a large enough segment of the population can obtain power from them.  This is a Wikipedia definition.

Infamous recent demagogues

Adolph Hitler, led the Nazi party to power in Germany by appeals to ethnic pride and conspiracy theories that blamed Jews for the nation’s economic troubles.

U.S. Senator Joseph McCarthy, famous for accusing many people in government and the entertainment industry of being communists.

U.S. Senator Ted Cruz, famous anti-government crusader whose obejctive seems to be to dismantle the U.S. Federal government.