orator or leader who gains power by arousing people's emotions and prejudices
a person who appeals to the prejudices and emotions of the people to gain power [n -S] / to act in the manner of a demagogue also DEMAGOG [v DEMAGOGUED, DEMAGOGUING, DEMAGOGUES]
is a leader who makes use of popular prejudices and false claims and promises in order to gain power.
A demagogue is a political leader who tries to get support by making use of popular prejudices, as well as by making false claims and promises and using arguments based on emotion rather than reason.