agitátor

n. one who agitates, one who causes unrest, propagandist, inciter, troublemaker

Agitator is a term for a person that actively supports some ideology or movement with speeches and especially actions.
See more at Wikipedia.org...

Noun
1. one who agitates; a political troublemaker
(synonym) fomenter
(hypernym) troublemaker, trouble maker, troubler, mischief-maker, bad hat
(derivation) agitate, foment, stir up

n. agitator, one who agitates, one who causes unrest, propagandist, inciter, troublemaker

n. agitator, inciter; activist