heckler — to harass (a public speaker, performer, etc.) with impertinent questions, gibes, or the like; badger.
militant — vigorously active and aggressive, especially in support of a cause: militant reformers.
radical — of or going to the root or origin; fundamental: a radical difference.
rebel — a person who refuses allegiance to, resists, or rises in arms against the government or ruler of his or her country.
agitator — If you describe someone involved in politics as an agitator, you disapprove of them because of the trouble they cause in organizing campaigns and protests.
revolutionist — a person who advocates or takes part in a revolution.
