1) Mr. Freeze
Though we’ve already seen Mr. Freeze on film, Arnold Schwarzenegger’s portrayal of the iconic villain did not do him justice. It’s been reported that he’ll be showing up on the small screen in Gotham, but given that show’s nature, the character will probably appear as Victor Fries in his pre-Mr. Freeze days. What we want is a full-blown version of the villain, Freeze gun and all.
The technology is certainly there to make the effects work, and though DC is going for a more grounded, gritty feel with their cinematic universe, adding in a villain like Mr. Freeze could work as long as they don’t go too campy with him, like Batman & Robin did.
Perhaps they could look toward Arkham City or Batman: The Animated Series for inspiration?