Who is Arkham Knight?

Who is the Arkham Knight?
Welcome to the very first Poll of Arkhamverse, new and more! YOU get to choose who Arkham Knight is, and who knows, your guess may be correct!

Add your Guess in comments!
Here are my guesses!

- Hush (Thomas Elliot )

-Red Hood (Jason Todd)

or Joker (brought from the dead)