The Klepto Conclave

The Galactic Thieves Guild is an interplanetary crime-ring, of which very little is known. All that is actually known about the Guild is that they are responsible for orchestrating the largest heists in recorded history, with their most infamous heists working around all security parameters and leaving no trace.

The guild is an extremely exclusive group, and nobody knows how one even joins. Nobody knows how many members there are, but it is known that they have an extremely talented individual or group of individuals in not only subtly and thievery, but hacking. As an incredibly political group, they are credited with leaking military documents, surveillance footage, phone calls and other incriminating data in order to oust political and military leaders/factions they consider to be immoral. 

With no member ever having been unmasked, it truly could be anyone.