Legion

And Jesus asked the man, saying, “What is thy name?” And the man said, “Legion” – because many devils were entered into him.

Legion (or Λεγεών) is an extremely powerful demonic entity, which itself is a grouping of multiple demons, that has been recorded in ancient history with the ability to possess humans. In more recent years it has come to be associated with Anonymous, where its malevolent presence is largely misunderstood and ignored.