A heckler is a person who interrupts a speaker or performer by shouting comments or insults, usually in a mocking or disruptive manner. Full definition
And though the proposal for free public college tuition for qualifying students that he announced last week elicited a sustained standing ovation at UB on Monday, some of his transportation initiatives also seemed to score with an appreciative crowd (though he was interrupted twice by hecklers who were quickly escorted from the auditorium). (buffalonews.com)
News footage of hecklers in Times Square shows many are braying, «We told you so.» (relevantmagazine.com)
This is, in fact, a lie; the over-used trope isn't even used by the most hack of hecklers at their first comedy gig. (totalpolitics.com)