interpret the subject heading however you like. but are they responsible ((partially or wholly) for creating threats to the public/universe/etc? Ultron would, arguably, be one of the big ones.
my contribution: It's my belief that Eric O'Grady could have gone one of two directions. but his tenure as a secret avenger is what pushed him into the villain column. Valkyrie and Venom did their best to kill him; w/o a moment's hesitation. it's like none of his sacrifices beforehand even mattered. he was under the influence of the Descendants. it's no different a situation from when they face Inverted teammates or Wanda when she was nuts. and before anyone starts talking about him being a life model decoy, Father (the head of the descendants) placed Eric's mind and memories into an artificial form. that makes him no different than current Tony Stark and James Rhodes (or, if you prefer, Vision). The only one from his past who didn't throw him under the bus was Taskmaster (the villain that they allowed to train and mentor the Iniative recruits). and that gets us to the current state of affairs. the individual who risked dying in an atomic blast to save the other Secret Avengers, kept a destructive weapon out of Norman Osborn's hands, and provided essential information to the resistance during Secret Invasion is hanging out at Baggalia.
anyways, what are your entries?