To be fair, both The Flash and Arrow are doing great job this season at trying to hide the identities of the main antagonists and keep wild masses guessing. There are a lot of Prometheus suspects, but that is already discussed in another blog post. What I want to say here is that our Prometheus still deserves his spot on Characters from the DC comics, despite showrunners specifically stating he's not Grant Morrison's Prometheus.
Well, he isn't per se, but character is quite similar in a lot of ways, that just simply cold not be ignored - just as Prometheus was one of the villains which could be characterized as "anti-Batmen", Prometheus on Arrow is an Anti-Arrow, spending just as much as Oliver did preparing for his crusade to become a direct opposite - psychotic but very skilled murderer. There are also visual similarities, such as color code and metal detailing of the mask, which distinguishes Prometheus from Arrow.
As we all know, Arrow loves to use Batman villains, which is probably a playful retaliation for both Count Vertigo and The Clock King, originally from Green Arrow's Rouges Gallery, being used in Batman media for decades.