Science fiction and fantasy fans have a long history of TV heartbreak. The genre, often invoking complex in-world mythologies and requiring an attention span that lasts longer than a single episode, often isn't suited for casual viewers who just want to sit in front of the tv and not think, or to televisions serialized nature. This may be one of the secrets behind the success of shows put out exclusively through Netflix and Amazon, where viewers can watch several episodes without the danger of forgetting everything during the intervening weeks. Often, it feels like television networks air shows even when they don't have any real confidence in them, putting them out just to test the waters to see what's popular. The quality of these shows can vary dramatically in terms of everything from originality to casting to effects. And more often than not, a real gem of a show can end up being swept away with all the other riffraff simply because the network didn't realise it was a 'sleeper hit' before it was too late. While the show sometimes has enough notice that they'll be able to bring a show to a definite (if often unsatisfying) conclusion, more often than not the cancellation comes after the final cliffhanger episode airs. It is only once the network starts receiving complaints that they realise they've made a mistake, and by then it's often too late. Here are ten sci fi series that, for one reason or another, were cancelled before they had the time to reach their full potential.