(n.) One prone to sound or excite alarms, especially, needless alarms.

Cain alarmist apache assassinator bloodletter bloodshedder bomber bravo burker butcher button man cannibal cutthroat desperado eradicator executioner exterminator garroter gorilla gun gunman gunsel hatchet man head-hunter hit man homicidal maniac homicide killer man-eater man-killer manslayer massacrer matador murderer pesticide poison poisoner scaremonger slaughterer slayer strangler terrorist thug torpedo trigger man