There are a few scary mobsters. i know people have said that tommy pitera "scared the scary guys". As someone said Tony Mirra was so scary other mobsters would try to pacify him by giving him stuff 'on the arm". However on the same token when donnie brasco was revealed he went into hiding since he knew som many of the mobsters he treated badly would want to kill him. Also ther was another guy that i have been researching about from the gambino family named Tony plate. From what i read he was always to mean and scared the shit out of a ton of people