10 Best Sci-Fi TV Shows Of The 21st Century, Ranked

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Science fiction is a genre that continues to stand the test of time. With space exploration, extraterrestrial beings, and alternate dimensions, sci-fi is always growing and changing, pushing itself to new heights as it feeds on current fears and politics. Many think of series like "Star Trek: The Next Generation" and "The Twilight Zone" as the best of the best, and those from the 21st century don't always immediately come to mind, even though some of the best of the genre is from the last three decades. 

There have been a lot of great science fiction shows in the 2020s so far, and that level of execution is present through the 21st century offerings. While they have built on what their 20th century predecessors put out, they have also pushed the genre in new directions with everything from planet colonizations and robot wars to time travelers and parallel universes. These are the best sci-fi TV shows of the 21st century that all science fiction fans should have on their watchlists.

• Cast: Christopher Eccleston, David Tennant, Matt Smith
• Creator: Sydney Newman
• Number of Episodes: 196
• Where to Watch: Amazon

"Doctor Who" follows the titular doctor and their companion as they move through time and help people. Though human, the doctor is technically a Time Lord, a species of people who are uniquely destined for the job. Each regeneration of the doctor brings a new actor to the role, and while they always have the same goals, they each tackle them differently.

While many know the series for its start in the 1960s, the 2000s iteration is the franchise at its best. With 15 seasons and six doctors, the revival continues what audiences loved about the original show — a narrative that can go in any direction because you never know what situation the doctor will encounter next. It leaves the TARDIS open for anything, which makes it feel spontaneous and fun.

"Doctor Who" has an average of 90% on Rotten Tomatoes, an impressive feat with so many seasons, and critics agree that it captures the spirit of the original series. "Fast, funny, scary and beautifully acted, it manages to be vibrant and fresh to appeal to a new audience while remaining utterly faithful to the spirit of the old show," David Winner wrote for The Financial Times in a Season 1 review.

• Cast: Millie Bobby Brown, Finn Wolfhard, Noah Schnapp
• Creators: Matt Duffer, Ross Duffer
• Number of Episodes: 42
• Where to Watch: Netflix

What happens when the planet has a connection to another realm that houses otherworldly beings? That's exactly what the 1980s-set Netflix series "Stranger Things" explores. Eleven (Millie Bobby Brown) is a young girl subjected to government experiments because of her psychokinetic powers, but she escapes and meets Mike (Finn Wolfhard) and his friends. When one of them is taken to the other dimension, which they dub the Upside Down, a chain of events that will threaten their town and the world is set in motion.

"Stranger Things" takes audiences on a memorable, nostalgia-filled journey across its five seasons. It presents a complex overarching villain in Vecna (Jamie Campbell Bower) and it combines science fiction with horror to create something that resonates with multiple generations. Younger audiences can follow Eleven and her new friends while adults can watch Winona Ryder as Joyce Byers and David Harbour as Jim Hopper as they try to figure out the best way to help their kids.

"Stranger Things" has a 90% critic score on Rotten Tomatoes. Reviews praise the storytelling and visual impact the series has, particularly as it leans into the '80s setting. Creators Matt and Ross Duffer pulled off the perfect balancing act. "'Stranger Things' is scary and cozy, heartening and grim," Richard Lawson said in his review for Vanity Fair. "It's also stylishly shot and scored by a captivating churn of 1980s synth swells."

• Cast: Joel Kinnaman, Michael Dorman, Sarah Jones
• Creators: Ronald D. Moore, Matt Wolpert, Ben Nedivi
• Number of Episodes: 50
• Where to Watch: Apple TV

"For All Mankind" follows an alternate timeline in which the Soviet Union initially wins the space race, claiming the first moon landing. What follows is the United States ramping up their programs to beat them at everything else, including having a mission base on the moon. As the Soviet Union continues to reach new landmarks, like the first woman on the moon, it puts more pressure on NASA to come out on top.

The Apple TV series is essentially showing us what could have been if we had continued to fund the space race at such a high level. The achievements in Season 1 alone are things we haven't done and aren't close to doing. While at times there are situations, typically related to sexism, that are difficult to watch, the project overall has an optimistic view of American society and our prospects in space.

"For All Mankind" has a 91% score on Rotten Tomatoes. Critics saw the vision of the first season, even if it wasn't executed as well as they would've liked, but the series only gets better with time. "It remains one of the most compelling watches on television, infused with awe for the cosmos and faith in humanity's ability to bridge gaps by working together," Nick Schager wrote for The Daily Beast.

• Cast: Anna Torv, Joshua Jackson, John Noble
• Creators: J.J. Abrams, Alex Kurtzman, Roberto Orci
• Number of Episodes: 100
• Where to Watch: Disney+, Hulu, Pluto TV

What happens when the FBI has a special division to investigate supernatural activity in a parallel dimension? That's what "Fringe" is all about. FBI agent Olivia Dunham (Anna Torv), eccentric scientist Walter Bishop (John Noble), and Walter's troubled son Peter Bishop (Joshua Jackson) work for the Fringe Division, managing the cases that need a special hand. They handle the cases that traditional science can't always explain.

"Fringe" combines the best of science fiction and procedurals. With the parallel realm and the strange science experiments related to it, the series contains oddities that audiences might expect from the genre, but it also has a "case of the week" format that fans of the best cop shows will enjoy. It's easily the closest thing to "The X-Files" in the 21st century.

With a 91% from critics on Rotten Tomatoes, "Fringe" received praise for its premise and how well it maintained it for five seasons. "It's classy, inventive sci-fi," wrote Michael Hogan in a review for The Guardian, while Kathy Blumenstock of The Washington Post praised the way the "fast-paced action zigzags between locations while special effects emphasize the sci-fi elements."

• Cast: Dan Stevens, Rachel Keller, Aubrey Plaza
• Creator: Noah Hawley
• Number of Episodes: 27
• Where to Watch: Disney+, Hulu, The CW

FX's "Legion" tells the story of a superhero, but not like other Marvel TV shows. David Haller (Dan Stevens) is a mutant with psychic powers. Because of his powers, which are mistaken for a mental health condition, he's regularly been detained in some form, but he breaks out and finds other mutants who help him understand the extent of his abilities.

"Legion" leans far more into science fiction than most superhero projects. There are parasitic mutants taking over people's brains, monsters from another realm, body swaps, and even someone trapped in an orb. The focal point of the story isn't how David fights the bad guys or develops his powers, but rather in how he begins to understand himself and his place in a world he realizes he knows nothing about.

"Legion" has a rating of 91% from critics on Rotten Tomatoes. Reviews highlight how well the series differentiates itself from other superhero shows and how visually beautiful it is to watch. "As superhero TV reaches critical mass, Hawley has helped the genre take a necessary evolutionary leap, mutating it into something refreshingly sophisticated and artful," said Kate Abbott of The Guardian.

• Cast: Tatiana Maslany, Dylan Bruce, Jordan Gavaris
• Creators: Graeme Manson, John Fawcett
• Number of Episodes: 50
• Where to Watch: AMC+, Netflix

Tatiana Maslany's Sarah Manning is a clone in "Orphan Black," for which she won an Emmy Award for outstanding lead actress in a drama series. Her life is turned upside down not only at the realization that she's a clone, but how she and her fellow lookalikes came to be and that someone wants them all dead.

"Orphan Black" takes science fiction in a bit of a political direction by having the clones be part of a scientific movement rooted in eugenics. The company behind it sees the clones as their property, tools to further their agenda, and the shady execs will do whatever they feel is necessary to protect their assets. It's different to the other sci-fi series on this list, but that's what makes "Orphan Black" stand out.

The series boasts a 93% score on Rotten Tomatoes, with critics complimenting Maslany's performance and the tone of the show. "It has a compelling premise, it weaves a distinctive tapestry of betrayal and loyalty and it offers its star, Tatiana Maslany, quite a few chances to prove her impressive versatility," Maureen Ryan wrote in a review for The Huffington Post.

• Cast: Anson Mount, Ethan Peck, Jess Bush
• Creators: Akiva Goldsman, Alex Kurtzman, Jenny Lumet
• Number of Episodes: 40
• Where to Watch: Paramount+

While there are several great "Star Trek" shows from this century, "Star Trek: Strange New Worlds" is the one that makes the cut here because it encapsulates everything that people love about this classic sci-fi franchise. Acting as a prequel to "Star Trek: The Original Series," the show follows Captain Pike (Anson Mount) and his time leading the crew of the USS Enterprise. A younger Spock (Ethan Peck) and James T. Kirk (Paul Wesley) make appearances as well.

"Strange New Worlds" is an absolute triumph, deftly taking one of the best science fiction franchises of all time and giving it new life. It presents long-time fans new material to chew on while also acting as a great entry point for newcomers. Crucially, it captures the sense of discovery and adventure that audiences fell in love with when "The Original Series" first aired, but modernizes it for a new generation.

With an impressive 94% critic score on Rotten Tomatoes, "Strange New Worlds" has received a lot of praise for its tone and execution. "The early episodes of 'Strange New Worlds' have a little bit of everything the franchise has tried over the years: exploration, diplomacy, action, even comedy," Alan Sepinwall wrote for Rolling Stone. "The breadth of what the show is trying to do is impressive, and a reminder of how elastic 'Star Trek' can be."

• Cast: Adam Scott, Zach Cherry, Britt Lower
• Creator: Dan Erickson
• Number of Episodes: 19
• Where to Watch: Apple TV

Apple TV's "Severance" takes the idea of a workplace drama to a whole new level. Employees of Lumon Industries go through a process in which they have a microchip implanted in their brains to give them two selves: an innie who works at the company and an outie who is the you outside of work. Neither remembers what the other does during their time. It seems like it could be a nice idea to just leave work at work. If only the intentions of the company were that pure.

Lumon has a scary amount of control over its employees. This isn't like any old job — once you are in, you're in for life, and it isn't clear why Lumon feels the need to microchip workers. The mystery of it all works well with the science fiction element of the innies and outies, creating a series with plenty of intrigue. The brilliance of the show is that the vast majority of us can relate to the innies on some level, making "Severance" a really disturbing watch for most people.

"Severance" has a 95% critical score on Rotten Tomatoes, where reviews compliment the world-building and the sense of dread that builds with every episode. "We marvel at the ingenuity of the concepts in 'Severance' and then are hit with what it all really means when our work self can never leave," Brian Tallerico said in a review for RogerEbert.com.

• Cast: Thomas Jane, Steven Strait, Dominique Tipper
• Creators: Mark Fergus, Hawk Ostby
• Number of Episodes: 62
• Where to Watch: Prime Video

Mars has long since been colonized in Prime Video's "The Expanse." This should be all fine and dandy, except that the Martians and the people of Earth are working against each other for resources and trying to extend their political reach, and that's without mentioned the Belters, people living in the asteroid belt between Mars and Jupiter.

"The Expanse" isn't a space exploration series. That has already happened. Rather, it's a show exploring the complex political system that happens when humanity puts populations across the galaxy. Each group has its own goals and it's interesting to see how each functions and fights for their place within the hierarchy. Effectively, it takes the elements of political dramas and drops them into a science fiction project with spaceships and mysterious wormholes.

The show has a 95% score on Rotten Tomatoes. Reviews highlight the political dynamics of the series and the special effects. USA Today's Kelly Lawler calls it "epic, whip-smart and addictive," while Salon's Sonia Saraiya describes it as "a gritty science fiction epic that combines the Earth-centric politics and space-travel details of 'Star Trek' with the wonder and romance of 'Star Wars.'"

• Cast: Edward James Olmos, Katee Sackhoff, Jamie Bamber
• Developer: Ronald D. Moore
• Number of Episodes: 76
• Where to Watch: Amazon

A reboot of the '70s series of the same name, "Battlestar Galactica" follows the residents of the Twelve Colonies of Kobol, a group of planets in space. After a devastating attack from the Cylons, a race of sentient robots that they created, they're left almost extinct. Fortunately, one ship — the show's namesake — made it out, and those on board decide to try and make a colony on a mythical planet they're not even sure exists: Earth.

The Syfy series includes everything there is to love about science fiction. It's set the far reaches of space. It involves robots rising up against their creators. It features exploration as the survivors try to find Earth after their home is destroyed. There's space ships and war and evil scientists, and it all comes together in a story that is one of the best space operas not just of the 21st century, but of all time.

"Battlestar Galactica" boasts a 95% rating on Rotten Tomatoes. The series received praise for its writing (even winning a Peabody for it in 2005) and special effects. "Even if you're skeptical of science fiction, 'Battlestar Galactica' will make a true believer out of you," Heather Havrilesky wrote for Salon.