Hourman
In late 2013, a rumor broke that Hourman might be making his way to the small screen in a CW show. While we haven’t heard anything substantial about the series since that report, I think that he’s a phenomenal character for TV, despite the lack of popularity. Still, the fact that I’d love to see him in a series doesn’t mean that Hourman wouldn’t be a quality addition to the DC cinematic universe as well.
Hourman was one of the founders of the first superhero team, the Justice Society of America. That alone is plenty of reason for why he should be a part of the more modern society. Admittedly, his age does make him a bit outdated, but Warner Bros. could always go with his son, Rick, instead of the elder Tyler. That would open the door to some father-son moments, which might be nice considering that the Justice League‘s two main characters are both without a father.