TV success is a fickle thing. There are shows which are fantastic from the outset that, for reasons unknown, get cancelled almost immediately shows that had incredible potential but didn't work in practice, or shows that promised the world, but fell flat on their face. On this list there are programmes should've gone the extra mile, that should've made it in the TV Hall of Fame: dramas that should've been on a level with The Wire, superior-to-Friends sitcoms, or Joss Whedon shows that could've been as big as Buffy. There are plenty of shows on this list that got their dues further down the line, but their initial rejection, non-renewal, and ultimate failure relegates them to "should've been awesome" status. Others simply had potential that they never lived up to. One of them was even a roaring success that, after a long hiatus, released a long-anticipated new season that was met with a chorus of "you have made a terrible mistake". (Ten points if you can guess which one).
10. Freaks And GeeksNo "should've-been-incredibly-successful but wasn't" list is complete without a nod to Judd Apatow's cult comedy Freaks and Geeks. Set in the 1980s, it centred on the lives of two very different siblings, "freak" Linda Cardellini, and "geek" (the incredibly adorable) John Francis Daley. The show follows both of these characters in their high-school subsets with an empathy and a realism that was largely without affectation. With the help of the supporting cast (James Franco, Seth Rogan, Jason Segal, need I say more?) Apatow managed to craft a sensitive but hilarious coming-of-age comedy. Whilst Freaks and Geeks circled dangerously close to after-school-special territory with storylines preaching acceptance of oneself and others where even the worst bullies had a back-story, it was consistently and outstandingly entertaining. Despite being nominated for various awards, including three Emmys, Freaks and Geeks was cancelled even before all the prepared episodes had been aired. These were then only shared due to a strong fan-led campaign, demonstrating the dedicated following that the show had even before cancellation.