VOICE OVER: Rebecca Brayton WRITTEN BY: Sammie Purcell
These sci-fi TV series made the future seem so much closer. For this list, we'll be looking at the most influential, beloved, and critically acclaimed science fiction shows to grace our screens. Our countdown includes "The Mandalorian," "Babylon 5," "Doctor Who," and more!

Top 20 Sci-Fi Television Series

Welcome to WatchMojo and today we’re counting down our picks for the Top 20 Sci-Fi Television Series.

For this list, we’ll be looking at the most influential,
beloved, and critically acclaimed science fiction shows to grace our screens. We won’t be including superhero or animated shows, so unfortunately that leaves out series like “The Boys” and “Rick and Morty.”

Which sci-fi series can you rewatch over and over? Be sure to let us know in the comments below.

#20: “The Mandalorian” (2019-)

“Star Wars” has been in our lives since “A New Hope” hit the big screen in 1977. But the franchise hasn’t always been consistently excellent, to say the least. When “The Mandalorian” came out in 2019, we weren’t sure how things were going to go. It was the first live action TV series in the franchise’s history, so the stakes were pretty high. Lucky for us, it premiered to near universal acclaim. The story of Mando and the freakishly adorable Grogu captured our hearts right from the very beginning. We would watch their relationship continue to develop until the end of time.

#19: “The Outer Limits” (1963-65)

Right before “The Twilight Zone” ended in 1964, another show came along to try and take its place. “The Outer Limits” might not have been quite as popular or had the longevity that the former series had, but it’s still a pretty fun watch. Much like “The Twilight Zone,” the show was an anthology series that delved into the darker ideas hiding behind science fiction. While the series only lasted a few seasons, it had a strong impact on the state of science fiction today. The show’s first season quickly earned a devoted following, and luminaries like Stephen King have sung its praises in more recent years.

#18: “Orphan Black” (2013-17)

Sometimes, all you need is an interesting premise and a stellar central performance. “Orphan Black” succeeds on both counts. Tatiana Maslany stars as Sarah, whom the audience quickly learns is only one of many identical clones. Maslany has the challenge of playing multiple characters, and she’s more than up to the task. The rest of the series dives into questions about humanity, morality, and other complex issues. “Orphan Black” walked a tight line between drama and humor and offered thought-provoking meditations on scientific ethics. With the fantastic Maslany at the helm, it couldn’t have gotten much better.

#17: “The Expanse” (2015-22)

What would happen if humans actually took over the solar system? We’re willing to bet things wouldn’t go that well. And if “The Expanse” is anything to go by, we’re definitely right. The Syfy series was based on a group of novels, and placed its central characters at the heart of political and social upheaval that eventually threatened the state of the entire galaxy. The plotting could be a little slow at times, but the commitment to promoting a noir-like sensibility was enough to keep audiences on the edge of their seats.

#16: “Red Dwarf” (1988-99; 2009-17)

Science fiction and comedy are difficult enough to do separately, and when you add them together, it can be near impossible to strike the right balance. But in the 1980s, and then later in the 21st century, “Red Dwarf” was able to do just that. The show follows Dave Lister, the last human alive, and his adventures alongside his holographic friend and a creature named Cat. This dysfunctional group of oddballs can barely do anything right, and their commitment to being absolutely useless makes them hilarious to watch. Imagine instead of watching Captain Kirk and Spock save the day, you’re watching a much more incompetent crew muck things up even more. That’s the essence of “Red Dwarf.”

#15: “Westworld” (2016-22)

By the end of its run in 2022, “Westworld” had somewhat fallen out of favor with the general populace. But it’s hard to forget the success and thrill ride of those first couple of seasons. Based on a 1970s film, the series was set in a theme park styled after the wild west, populated by hyper-realistic robots created to serve the whims of the park-goers. The series tackled issues of ethics and sentience with care, but never backed down from the cruelty inherent to the world. “Westworld” was shocking and smart, and featured amazing performances from the likes of Ed Harris, Evan Rachel Wood, and Anthony Hopkins.

#14: “Babylon 5” (1993-98)

The best science fiction series incorporate something more than just aliens and space into their storylines. “Babylon 5” did just that. The 1990s series focused on the staff of a military space station, and was as much about diplomacy as it was about space travel. The humans on the station were tasked with dealing with representatives from different alien races, the fallout of intergalactic war, and so much more. The series dealt with important questions and critiques of government authority and totalitarianism. This made the show both entertaining and thought-provoking.

#13: “Dark” (2017-20)

It’s hard to find a show with a more apt title. Netflix’s “Dark” is a German-language program that offers one of the bleakest portraits of humanity ever seen in a sci-fi show. Initially, the series interrogates how one child’s disappearance affects four families in a small town. As the audience learns more about the child, the show suddenly turns into a time travel saga spanning multiple decades. Equal parts “Stranger Things” and “Twin Peaks,” in 2017 “Dark” was one of the best shows on TV. It’s also one that’s so complex, we’re sure we could rewatch it and be surprised all over again.

#12: “Lost” (2004-10)

For some, “Lost” might not have stuck the science fiction landing. But there’s no denying that for seven years, the series dominated the culture in a way that arguably hasn’t quite been replicated since. “Lost” follows the survivors of a plane crash as they navigate the strange island they’ve landed upon. The first few seasons are characterized by terrifying smoke monsters, polar bears in tropical climates, and a strange man who lives in an underground hatch. These mysteries made “Lost” one of the most compelling series on television, and as the show went on the puzzles kept on coming. It’s up to you to decide how you feel about the ultimate conclusion, but we have to give credit where it's due.

#11: “Firefly” (2002)

If there’s one thing we can all agree on, it’s that “Firefly” deserved more! After the success of Joss Whedon’s earlier series “Buffy the Vampire Slayer,” it’s pretty amazing that “Firefly” didn’t get its flowers when it was on the air. The show starred Nathan Fillion as Mal, the captain of a ship called Serenity. Mal heads a crew of rebels, and each episode follows their outlandish adventures. What made “Firefly” so special was the chemistry between the characters and by extension the performances of the actors who played them. The series only lasted one season, unfortunately. But during its initial run, and in the years since its release, it’s earned an incredibly devoted fanbase.

#10: “Stranger Things” (2016-)

When “Stranger Things” premiered on Netflix in 2016, there was no way of knowing it would become one of the streaming service’s most important original shows. But with a little bit of luck, good writing, and a stellar cast, it did just that. “Stranger Things” takes place in the fictional town of Hawkins, Indiana. The story centers around a group of boys and the friendship they strike up with a strange new girl who mysteriously appears in town. As the series has gone on, the cult of love surrounding the cast and characters has continued to grow. The 1980s nostalgia only adds to the popularity, and it gives the show a chance to riff on classic sci-fi storytellers like Stephen King and Steven Spielberg.

#9: “Quantum Leap” (1989-93)

When it comes to science fiction, the creators we love can never get enough of all things quantum. But we still think the best use of quantum physics in a television show might have peaked back in 1989 when “Quantum Leap” began. The show stars Scott Bakula as a physicist who tests his project accelerator prematurely and finds himself leaping uncontrollably through time. But this isn’t just your average, everyday time travel. When Bakula leaps, he takes the place of other people and must “put right what once went wrong” in order to leap again. Thanks to great writing and brilliant chemistry between the two leads, the show was a perfect mix of sci-fi, comedy, and social commentary.

#8: “Fringe” (2008-13)

What do you get when you combine an FBI agent, a disgraced former scientist, and his renegade son? Why, “Fringe,” of course! This Boston-based sci-fi series followed the ever-successful mystery of the week format, but had larger mysteries lurking under its surface. Every week, our favorite characters would team up and use what’s called fringe science to uncover the truth about parallel universes and other unexplained occurrences. We love the science fiction aspects of this show, but our favorite part is the complex romance between the characters played by Anna Torv and Joshua Jackson.

#7: “Stargate SG-1” (1997-2007)

Out of a movie that received mixed reviews, came a beloved franchise. 1994’s “Stargate” gave birth to multiple television shows, such as “Stargate Atlantis” in 2004. But the best thing the film helped create was “Stargate SG-1.” This spin-off series starts roughly one year after the conclusion of the film and centers on a military unit sent to explore the galaxy. It takes on the typical storylines of a science fiction show set in space, with plenty of alien battles galore. But, as much as “Stargate SG-1” is about intergalactic war, it also incorporates plenty of humor and pop culture references, making it more light-hearted than other similar series.

#6: “Star Trek: The Original Series” (1966-69)

Over the years, “Star Trek” has spawned numerous spin-offs and reboots, not to mention dozens of series and films that were clearly inspired by it. But those stories would be nothing without the OG. “Star Trek: The Original Series” premiered in 1966, introducing the world to Kirk, Spock, Scotty, Bones, Uhura, and Sulu for the first time. While the original run of “Star Trek” is very much a product of its time, it often showed levels of creativity, imagination, and depth never before seen in sci-fi storytelling. For all of its faults, it started a revolution. Its legacy in the realm of science fiction cannot be overstated.

#5: “Battlestar Galactica” (2004-09)

If at first you don’t succeed, try and try again! The original “Battlestar Galactica” first premiered in 1978. While that series has its fans, it wasn’t universally beloved. But with the 2004 reboot, “Battlestar Galactica” finally got its laurels. The show follows the last of humanity as they traverse the galaxy after a decimating attack from a robot race called the Cylons. It’s a political and military thriller wrapped up in a sci-fi show. Yet some of the series’ best moments come from the complicated and sometimes toxic romance between the show’s leads, Starbuck and Apollo.

#4: “The X-Files” (1993-2002; 2016-18)

Talk about a will they, won’t they. “The X-Files” may not have invented the concept, but it is one of the shows that did it the best. Even though we were all tuning in to see if the two attractive leads would finally do the deed, we were also there for the mystery. The show brings together FBI Agents Mulder, a supernaturalist, and Scully, a doctor, to investigate the paranormal together. Their differing belief systems initially set them at odds, but their differences are ultimately what make them work so well together. That chemistry, along with clever writing and masterful storytelling, make the show a winner.

#3: “Doctor Who” (1963-89; 2005-)

When a show has this kind of staying power, you know it’s a good one. “Doctor Who” premiered on the BBC in 1963. After an incredible initial run of twenty-six seasons, it went off the air in 1989. However, to fans’ delight, it was revived in 2005. The Doctor is an alien who travels through time via a machine called a TARDIS disguised as a telephone box, helping those in need. Since its inception, the show has become an integral part of British culture. Because the Doctor sometimes has to regenerate his body, the producers must regularly change the actor who plays him, which has helped to keep the show alive for decades.

#2: “Star Trek: The Next Generation” (1987-94)

For many Trekkies, “TNG” represents the best of “Star Trek.” And considering how many films and series have come out of the franchise over the last six decades, that’s saying something. The show builds off the success of the original, introducing new characters and making them indispensable. Most notably, the series gives us Jean-Luc Picard, the diplomatic captain of the Enterprise played by Patrick Stewart, who serves as a stark contrast to Kirk’s brash nature. “The Next Generation” became one of the most popular sci-fi shows of all time, and its status as a genre icon still remains strong.

#1: “The Twilight Zone” (1959-64)

Though many shows have tried, including Netflix’s “Black Mirror,” few anthologies have reached the critical heights of “The Twilight Zone.” Equal parts horror and science fiction, the show had its heyday in the 1960s, perfectly capturing paranoia and surrealism in television-sized bites. Decades after the show premiered, the images it created still stay with us. Whether it’s the creature on the airplane wing or the terrifying pig masks, everyone has an episode that scared the daylights out of them. Arguably the most influential series ever, “The Twilight Zone”’s legacy lives on through the many artists and creators it has inspired over the last half century.