6) Generation X
Although its vast and hugely-populated world would be perfectly suited to TV, the X-Men franchise has never had a successful live-action television show. Fox are currently working on a few – like Legion and Hellfire – but things could have kickstarted a lot earlier if this series worked out.
A TV movie produced back in 1996, Generation X was actually the very first live-action take on the X-Men universe. Though it wasn’t exactly faithful to the source material, it did include several characters from the comics – like Jubilee, Banshee and Emma Frost (the latter two being the team leaders in this incarnation).
Unfortunately, the pilot was incredibly cheap and cheesy and the planned series never materialized. Thankfully, only four short years later, Bryan Singers’ X-Men restored the mutants to their proper place at the forefront of superhero adaptations. Shame an X-Men TV series couldn’t have happened as well, though.