Sometimes even the most beloved science fiction series don’t garner enough of an audience for the network to justify producing more seasons. This is a tale at least as old as “Star Trek: The Original Series” which, despite a vocal fan base, was canceled after three seasons. This trend has continued on, with cult classic shows either not finding their audience until after cancellation or not living up to network expectations. Sci-fi shows often come with higher price tags than a sitcom or reality show and face a higher cancellation risk if they can’t build that sizable audience in time.

Even accounting for the financial realities of the industry, these untimely cancellation notices still hurt decades later. These are fan-favorite shows bringing fresh stories to the genre that just didn’t quite get the chance to tell their full tale. Some of these shows have grown even more popular in the years since, but those original cancellations still stand. Here are 12 sci-fi TV shows that were canceled way too soon and are still worth checking out.

After creating “The X-Files,” writer and producer Chris Carter created another sci-fi horror show involving FBI agents, “Millennium.” The Fox show followed former FBI profiler Frank Black (Lance Henriksen), who had the unique ability to see through the perspective of murderers and other criminals. After resigning from the bureau, Black worked as a consultant for a shadowy organization known as the Millennium Group. Initially pursuing serial killers like he did with the FBI, Black stumbled across supernatural threats as he uncovered the disturbing truth behind the group.

Generally, “Millennium” was a much darker show than “The X-Files,” reflecting pop culture’s resurgent interest in serial killer stories at the time. As hinted by the title, the show capitalized on the impending year 2000, though it would be canceled prior to reaching its titular year. Black resurfaced in a crossover episode of “The X-Files” after its cancellation to provide closure, albeit unsatisfactorily. A serial killer show with paranormal undertones, “Millennium” was ahead of its time, beyond the apocalyptic anxiety within its premise.

As “The X-Files” neared the end of its original run, it spawned the Fox spin-off series “The Lone Gunmen” in 2001. The show stars the titular conspiracy theorist trio from the main series: John Fitzgerald Byers (Bruce Harwood), Melvin Frohike (Tom Braidwood), and Ringo Langly (Dean Haglund). Continuing the group’s usual paranoia-fueled investigations, the Gunmen delve into alleged government cover-ups and clandestine plots to steer the course of civilization. While the stakes are often high, the show has a much lighter tone than “The X-Files,” sometimes veering into outright slapstick comedy.

Despite its sole season ending on a cliffhanger and positive critical reviews, “The Lone Gunmen” was canceled due to low ratings. Several lingering plot threads were resolved in the ninth season of “The X-Files,” seemingly ending with the trio’s heroic deaths. “The X-Files” Season 12 suggested that a Lone Gunman faked his death, but it still would’ve been nice to see the three characters thrive in the spotlight.

After the lackluster reaction to 2003’s “Terminator 3: Rise of the Machines,” the franchise found new life on television with Fox’s “Terminator: The Sarah Connor Chronicles.” Set in the aftermath of “Terminator 2: Judgment Day,” Sarah Connor (Lena Headey) and her son John (Thomas Dekker) learn they must prevent a cybernetic armageddon. The Connors are pursued not only by other Terminators sent from the future to kill them, but also the FBI for their destructive actions in “Judgment Day.” On the run, the duo is joined by the heroic Terminator, Cameron (Summer Glau), reprogrammed to defend them and ensure John fulfills his destiny.

Running for two seasons, “The Sarah Connor Chronicles” found fun and exciting ways to explore the wider Terminator mythos after “Judgment Day.” Headey made for an effective Sarah Connor, while Glau was always a standout in her performance as Cameron, bringing immense heart to an otherwise cold world. And for a network television show, the series featured plenty of high-octane action, worthy of its iconic franchise. One of the best TV shows based on a movie, “Terminator: The Sarah Connor Chronicles” played masterfully with its richly established sandbox while adding its own twist. 

The 2006 CBS series “Jericho” begins with the end of the world as we know it, opening with 23 major American cities hit by nuclear strikes. The resulting collapse of modern civilization in the United States unfolds from the perspective of the small Kansas town of Jericho and its residents. As Jericho tries to reposition itself as a self-sufficient community without federal resources, tensions rise with the neighboring town of New Bern. This is interrupted by the arrival of a new military government, the Allied States of America, which imposes its own repressive rule over the community.

From its post-apocalyptic tribalism to its conspiracy-driven central mystery, “Jericho” avoids the overwhelmingly bleak tone that usually comes with its premise. That said, this is a show that doesn’t pull punches, especially as Jericho’s external conflicts escalate. The show’s got a solid ensemble cast led by Skeet Ulrich, with a pre-“Walking Dead” Lennie James among its standouts. “Jericho” is one of the best shows that aired for two seasons, offering tantalizing questions and plot directions with its explosive premise.

Let’s get the obvious thing out of the way first and acknowledge the toxic allegations surrounding series creator Joss Whedon that make him a problematic figure. With that said, he was also the principal creative force behind several beloved sci-fi television series that were canceled in short order. One such ill-fated series is Fox’s “Firefly,” a space Western set in a largely lawless solar system despite the presence of a totalitarian Alliance. The story follows Captain Mal Reynolds (Nathan Fillion), who leads his crew on a small spacefaring freighter, often on smuggling contracts among the frontier colonies.

What “Firefly” does so well is fill out a Western-influenced world and mythos in its 14-episode run. The other strong quality is the ensemble cast making up the Firefly’s crew, each with their own idiosyncrasies and foibles that play well off each other. Mal Reynolds is made in the mold of Han Solo, but Fillion brings plenty of his own irascible charm to make the character his own. One of TV’s best one-season sci-fi shows, “Firefly” offers a lived-in and lawless look at life on the cosmic frontier.

Another Whedon-created sci-fi show on Fox that got its marching orders less than two full seasons in was “Dollhouse.” Premiering in 2009, the show starred “Buffy the Vampire Slayer” alum Eliza Dushku as Echo, whose memories were repeatedly erased to accommodate temporary mental programming based on wealthy client requests. However, Echo was unique among the other Dolls in that she retained a fraction of her memory between each wipe, gradually developing a sentient personality. As the Los Angeles-based Dollhouse struggled to maintain control of its Dolls, Echo tried to avoid being detected as operating outside her programming and exiled with other broken Dolls.

“Dollhouse” was a much headier sci-fi story than Whedon’s other work, exploring the nature of identity and purpose through its near-future lens. Dushku, who also served as a series producer, gave a commanding performance as Echo, drastically shifting with each reset while retaining an underlying core personality. The series was canceled in the midst of production on its second season, though the 13-episode season was ultimately aired in its entirety. Holding a strong ranking among Whedon shows, “Dollhouse” featured the writer and producer at his most existential.

The 1999 novel “Flashforward” by British author Robert J. Sawyer was adapted into the 2009 ABC sci-fi series “FlashForward.” The show starts with a global event that has seemingly everyone on the planet lose consciousness for 137 seconds, receiving a vision of their lives six months into the future. The story centers on a team of Los Angeles-based FBI agents, focusing on partners Mark Benford (Joseph Fiennes) and Demetri Noh (John Cho) as the team tries to find out what occurred and if this is an isolated incident while reconciling with each of their individual premonitions.

“FlashForward” boasts an intriguing core premise, as the audience tries to figure out what each of the main characters just witnessed from their sneak peek. Particularly gripping is Noh’s premonition, or lack thereof, as he realizes he has to try to avert his death based on the flashforward’s implications. The series ended with an unresolved cliffhanger, but the show’s sole season told a compelling and well-crafted story. A series with a great narrative hook and well-rounded ensemble cast, “FlashForward” takes full advantage of its potential.

One of the most universally acclaimed sci-fi series of the 21st century was the 2004 reimagining of “Battlestar Galactica,” depicting humanity’s fight against the Cylons. The year after the show’s conclusion, the prequel spin-off “Caprica” premiered on Syfy, set 58 years before the events of its predecessor in the Twelve Colonies of Kobol. When wealthy tech industrialist Daniel Graystone (Eric Stoltz) loses his daughter to an unexpected tragedy, he becomes obsessed with resurrecting her through technology. This leads him to team up with lawyer Joseph Adama (Esai Morales) as Graystone uses his resources to create the Cylons.

Most of the sharp character development that made “Battlestar Galactica” so enjoyable is present in “Caprica,” albeit framed much differently. This is largely elevated by Stoltz and Morales’ central performances, with the story exploring the lengths they’ll go to in order to extinguish their grief. Unfortunately, the show’s look at the franchise’s early days were cut short, with the series canceled before it completed its broadcast run. And with the “Battlestar Galactica” reboot no longer in development at Peacock, the early “Caprica” cancellation continues to sting years later.

Filmmaker Steven Spielberg teamed up with prolific “Star Trek” screenwriter and producer Brannon Braga for the 2011 Fox series “Terra Nova.” The show takes place in the 22nd century, with Earth suffering from overpopulation and degrading environmental conditions when a temporal rift is discovered. This leads to the creation of a colony on a parallel Earth during the planet’s Cretaceous Period, complete with the presence of dinosaurs. Former police officer Jim Shannon (Jason O’Mara) and his medical expert wife Elisabeth (Shelley Conn) are among the prominent colonists, joined by their three children.

While the “Terra Nova” ratings ticked up for its finale, the show was canceled by Fox after a single season. This was likely due to the series’ high price tag, particularly in bringing its time-bending world to life. To its credit, the show boasts a cinematic-level presentation, helping elevate the action. A survivalist tale that combines otherworldly colonization with dinosaurs — always a winning choice — “Terra Nova” provides ambitious thrills.

While Karl Urban has found incredible success starring on Prime Video’s “The Boys,” his first major starring role in an American television series was Fox’s “Almost Human.” Urban played John Kennex, a police detective in New Pittsburgh in the year 2048 who is paired with android partner Dorian (Michael Ealy). Together, the duo solved crimes around the city as Kennex recovered from a devastating gangland ambush that killed most of his squad and left him losing significant portions of his memory. Along the way, Dorian provided amusing observations about Kennex, often inadvertently deflating his normally gruff nature as the two learned to work together.

“Almost Human” was a sort of buddy-cop crime drama that really benefited from its two lead actors’ rapport. Urban and Ealy settled quickly into their good cop/bad cop archetypes while the case-of-the-week format was filled out well by the futuristic setting. New Pittsburgh was a future that alternated between bright and bleak, with the show demonstrating the wonders of advanced tech while emphasizing it as a catalyst for rampant crime. Lasting only a single season, “Almost Human” had a great cast and an interesting setting, but just couldn’t maintain high-enough ratings for the network.

The classic ’70s sci-fi movie “Westworld” was adapted into a big-budget HBO original series in 2016, retaining writer Michael Crichton’s initial premise. The show takes place at an elaborate theme park created by Delos Inc., which recreates various historical periods for guests to live out their fantasies unfettered. Populating these regions are highly advanced synthetic beings who have their memories wiped regularly to welcome new sets of guests. However, the androids begin to not only retain their memories, but develop sentience, leading to a rebellion against their corporate masters.

“Westworld” really takes Crichton’s theme-park-gone-wild premise and uses it as a springboard for a more ambitious sci-fi story. The show asks heady existential questions about purpose and identity through its synthetic characters as they finally gain agency. This is all couched in between a mix of action that progresses from Western-tinged to something more distinctly sci-fi. Canceled amid negotiations for a fifth season, “Westworld” might not be as over as we thought as fans wait for a satisfying conclusion.

One of the most ambitious sci-fi series produced by Netflix was “Altered Carbon,” set in a thoroughly dystopian future. Humanity has found a way to outlast death, transferring their consciousness and memories into a device implanted into a new body when their current one expires. The show follows former soldier Takeshi Kovacs (Joel Kinnaman), who is tasked with investigating the murder of Laurens Bancroft (James Purefoy), one of the richest men in the world. The second season takes place 30 years later, with Kovacs now in a new body (played by Anthony Mackie) as he searches for his missing lover Quell Falconer (Renée Elise Goldsberry).

Based on the novel by Richard K. Morgan, “Altered Carbon” is one of Netflix’s most visually stunning series, with the streamer sparing no expense in adapting the sci-fi tale. Each season has a different mystery at its core, the second of which is particularly personal for Kovacs, keeping the audience invested, too. The change in lead actors and driving case helps keep the show fresh, maintaining the overarching world but changing up the energy behind it. Canceled after two seasons at Netflix, “Altered Carbon” was big-budget cyberpunk television done right.