One of my all-time favourite TV shows is Joss Whedon's Firefly.
Firefly is set in the future. When Earth's resources became used up, other planets were terraformed. The Alliance decided that they should have control over all of the planets, but the Independents fought to keep their independence. The Alliance won, meaning that many of the Independents live on the fringes of the Universe making a living however they can. There's no way of doing the show justice without you watching it but it has Nathan Fillion, space cowboys and Whedon's signature one-liners. What more could you want?!
Unfortunately it was doomed from the start, with its episodes being aired out of order when it was on TV for the first time. For some reason Fox then decided to cancel what was a fantastic show with a very strong fan base. I never saw it when it first aired, as it's an American show and we didn't have Sky at the time. But the fans fought hard for Firefly to be brought back, and a few years later Serenity the movie was made to tie in some of the lose ends left after its sudden cancellation.
Unlike many shows that go on for a few series too many, Firefly was cut off before it even reached its prime, but the episodes that have been made are unmissable. Be warned though, you will be left feeling so disappointed that it was cancelled when you reach the end of the series!
If you are already a Firefly fan, well done! You pass my friend test! :)