Here is a list of the best sci-fi shows and best sci-fi series of all time, as ranked by hundreds of Ranker voters. This list includes long-running sci-fi TV shows like Doctor Who as well as some of the best canceled shows of the genre. Science fiction TV shows have been around for decades, and some of the longest running shows have fallen into this category. Popular shows such as Star Trek have enjoyed several incarnations, and fan-favorite shows like Firefly and The X-Files have made the crossover from TV to the big screen.

Thanks to networks like SyFy, FX, and The CW, new sci-fi TV shows premiere every year. Sci-fi series like The Expanse, Orphan Black, and The 100 continue to raise viewership ratings and grow fan bases. Netflix has also contributed to the science fiction genre with their original series Stranger Things, which was met with rave reviews.

Vote for your favorite science fiction shows to move them to the top of the list, or press re-rank to create your own list of your favorite science fiction series. Be sure to stop by to vote on the best British sitcoms and best current TV shows airing right now.

Are you a sci-fi fan? Check out this list of current sci-fi shows to watch.