8) Felix Faust (Arrow)
He may have already made an appearance in Constantine (not that it was particularly memorable), but Arrow could definitely do something interesting with Felix Faust now that the show appears to be embracing magic.
One of the most powerful sorcerers in the DC Comics Universe, Felix is thousands of years old and, unlike Damien Darhk, is someone who relies solely on magic and not any sort of physical prowess. He’s perhaps a little too similar to season four’s big bad to take on the role next year, but could make for an interesting enough threat over the course of a couple of episodes.
If the team behind Arrow really want to stick to continuity, they could bring back Mark Margolis (Breaking Bad) in the role, but seeing as he was killed off in Constantine, he would obviously have to appear only in Oliver Queen’s flashbacks.