Though the sci-fi genre lends itself to franchises and sequels, there are many great movies that never got the follow-up installments they deserved. Many of these films had their sequels planned and were well on their way to pre-production when momentum stalled or external forces got in the way of their development. In some cases, the reason these sequels never saw the light of day was because the original movies underperformed at the box office, making the second installment a risky investment no one wanted to attach their name to.

Of course, there are some sci-fi movies that should never get remakes or sequels, but all of these films lend themselves to a continuation of their stories. The original movies created fully fleshed-out worlds with many exciting details that could be expanded upon in additional works. It's always a significant disappointment when it's not the second film that's canceled but the third or fourth installment. This means the thrilling and long-awaited conclusion to the story is cut short. Fortunately, most of these movies tell complete narratives, satisfying audiences and providing some closure.

10 District 9 (2009)

Sequel: District 10

The director of District 9, Neill Blomkamp, is in conversation with humanity's long history of segregation and xenophobia through the film's story. It directly tackles apartheid in South Africa through the lens of the aliens who are trapped in an internment camp upon their arrival on Earth. Starring Sharlto Copley as Wikus, a man whose DNA is spliced with that of the aliens and who gets an inside look into the discrimination and severity of treatment they face, District 9 was a critical and box office success.

District 10, the long-awaited potential sequel to District 9, has been discussed many times since the first film premiered, but no concrete updates have been given.

District 9 is an alien invasion movie where the aliens are peaceful, setting it apart from other additions to the genre. District 10, the long-awaited potential sequel to District 9, has been discussed many times since the first film premiered, but no concrete updates have been given. Though there would certainly be an audience excited to experience the next part of Wikus' journey and find out if conditions ever improved for the aliens, it will be a long time before any news of District 10 comes.

9 Vanilla Sky (2001)

Sequel: Vanilla Sky 2

Tom Cruise might be best known for his contributions to the action-adventure genre, but Vanilla Sky proves that he's just as capable of holding his own in sci-fi. The mind-bending thriller begins with David (Cruise) telling the story of how his idyllic life went down in flames and he lost everything. However, as David chronicles his tragic tale of betrayal and death, it's easy to see holes in his story and notice the surreal elements that make Vanilla Sky so confounding.

It soon comes to light that David has been living in a simulation, and nothing is as it seems in Vanilla Sky. The end of Vanilla Sky is famously ambiguous and leaves David's fate unknown, making it infuriating that we never got a Vanilla Sky sequel. There was plenty of potential for another installment to the story, and Cruise and Crowe have worked together multiple times. Unfortunately, after over twenty years, it's likely that David's future will always remain a mystery.

8 Event Horizon (1997)

Sequel: Even Horizon 2

Boasting a stellar cast and some gory horror elements, Even Horizon has become a cult classic in recent years. With the likes of Laurence Fishburne and Sam Neill leading the cast, Event Horizon was directed by Paul Anderson in the wake of his success with Mortal Kombat. One of the biggest complaints lodged against Event Horizon was that it didn't have an original story and relied on the flashy nature of its visuals. However, a cohesive look and atmosphere is a vital piece of any sci-fi project.

The concept of Event Horizon does lend itself to future installments, as the film has received frequent comparisons to the Hellraiser franchise.

Unfortunately, it was the box office failure of Event Horizon that has ensured that the underrated campy sci-fi classic has never gotten a sequel. However, the concept of Event Horizon does lend itself to future installments, as the film has received frequent comparisons to the Hellraiser franchise. Today, audiences would appreciate a return to a classic like Event Horizon, and seeing some of the iconic stars return would make the sequel worth watching.

7 Oblivion (2013)

Sequel: Oblivion 2

A unique blend of action and sci-fi, Oblivion makes good use of Tom Cruise as its protagonist, and it's not surprising that there have been so many cries for an Oblivion sequel. Cruise is known for his franchise work and is a big enough star to warrant many additional installments, but Oblivion didn't have the impact that a successful sci-fi blockbuster hopes for. Directed by Joseph Kosinski, Oblivion is set in a dystopian future where Jack (Cruise) is one of the last remaining humans doing clean up on Earth following a war with invading aliens.

The end of Oblivion sets up an exciting potential future and leaves the door open for Cruise to return as Jack. Though there are many twists and turns in Oblivion, it's relatively easy to follow, and it crafts a larger world worth exploring. One of the most exciting niches of sci-fi is stories that grapple with how people handle the rebuilding of society after a world-ending event. Though there are no plans for Oblivion 2, it would make sense for us to find out more about Jack's legacy.

6 Alita: Battle Angel (2019)

Sequel: Alita: Battle Angel 2

Ever since Alita: Battle Angel premiered in 2019, audiences have been wondering when a sequel would come out. Based on the manga Battle Angel Alita, the visually immersive and well-crafted movie was a mild box office success, but with such a high budget and so many resources allocated to the advanced CGI technology, it struggled to turn a profit that would've ensured a second installment. Directed by Robert Rodriguez, the film boasts his classic, fast-paced action sequences and sleek visual style.

Alita: Battle Angel has a strong following, and there's plenty of material to inspire additional films.

The hopes and demands for an Alita: Battle Angel sequel haven't diminished since 2019, and it's possible that another movie might come one day, but the chances keep getting slimmer. James Cameron, one of the writers and producers, is fully entrenched in his Avatar sequels, placing any hope for an Alita follow-up on the back burner. However, Alita: Battle Angel has a strong following, and there's plenty of material to inspire additional films.

5 The Divergent Series: Allegiant (2016)

Sequel: Divergent: Ascendent

Following in the footsteps of The Hunger Games and many of the most popular YA dystopian sci-fi and fantasy series of the 2010s, the Divergent movies made a splash. The original, Divergent, released in 2014, performed well and was enough of a success to warrant the second and third books to be adapted for the screen. However, unlike The Hunger Games, the Divergent films couldn't sustain a four-movie franchise, and splitting the third book into two installments turned out to be a death sentence.

​​​​​​​The third movie, Allegiant, left off on an unbelievable cliffhanger, and Tris' (Shailene Woodley) story remained incomplete when the planned conclusion, Ascendent, never got made. It didn't come as a complete surprise, as Divergent was never as well received as The Hunger Games. Additionally, Insurgent and Allegiant got progressively worse reviews, so the writing was on the wall. However, it's a shame that Veronica Roth's narrative never reached its conclusion and that the Divergent franchise will always be unfinished. ​​​​​​​

4 E.T. The Extra-Terrestrial (1982)

Sequel: E.T. II: Nocturnal Fears

The beloved family sci-fi classic, E.T. the Extra-Terrestrial, is Steven Spielberg's best movie about aliens and an enduring addition to the genre for a reason. Though E.T. was extremely successful, and a sequel likely would've garnered plenty of attention, Spielberg decided not to move forward with his plans for the potential second film. On one hand, this is too bad, as this could've made E.T. a Spielberg franchise on par with Jurassic Park or Indiana Jones​​​​​​. However, I understand why Spielberg didn't want to make the sequel.

It's clear that Spielberg understands how to make a great blockbuster sequel, but E.T. the Extra-Terrestrial never got this treatment.

In some ways, E.T. is a perfect movie, and trying to recapture its magic would've been a disservice to the original. However, if anyone would be capable of creating a sequel that justifies itself and pushes the story forward, it would've been Spielberg. Though Elliott's (Henry Thomas) journey with E.T. was over, that doesn't mean the next project couldn't have tackled another family who needed him. It's clear that Spielberg understands how to make a great blockbuster sequel, but E.T. the Extra-Terrestrial​​​​​​​ never got this treatment.

3 Independence Day: Resurgence (2016)

Sequel: Independence Day 3

The original Independence Day came out in 1996 and stars Will Smith as Steve in a movie that helped link the disaster and sci-fi genres in a massive blockbuster event. Twenty years later, Independence Day: Resurgence hit theaters, featuring many of the original cast and characters, but with Liam Hemsworth as the new protagonist, Jake Morrison. Set years after the events of the first movie, Independence Day: Resurgence sees the characters grapple with the reality of alien invasion and attempt to keep Earth prepared for threats.

Though Independence Day: Resurgence was lauded for its visual effects, the planned follow-up hasn't seen the light of day. The sequel struggled to differentiate itself from its more successful predecessor and failed to justify its existence since the conclusion of Independence Day felt like a solid ending to the story. The director, Roland Emmerich, discussed plans for what Independence Day 3 might have looked like and its intergalactic scale, but for now, there are no plans for the next sequel (via Collider).

2 John Carter (2012)

Sequel: The Gods of Mars

Taylor Kitsch, best known for his performance in the sports TV drama Friday Night Lights, starred in the failed sci-fi franchise John Carter. As the titular character, Kitsch brought to life the lead character from Edgar Rice Burroughs's beloved science fiction novels. However, in 2012, John Carter underperformed at the box office, and any future for the potential trilogy of films stalled out before it could properly begin. Full of intricate visual effects and a significant budget, these factors ended up tanking the project.

Though the premise of John Carter is somewhat strange, it's a classic space adventure, and Kitsch is a believable hero. In recent years, John Carter has become a cult film and garnered recognition within the sci-fi community as a film that was unjustly lambasted. The fact that John Carter brought to life lesser-known intellectual property and attempted to fight against the oncoming onslaught of sci-fi movies that were part of long-running franchises or were remakes sets it apart from many of its contemporaries.

1 The Fifth Element (1997)

Sequel: The Fifth Element 2

Bruce Willis and Milla Jovovich star in the cult classic sci-fi movie The Fifth Element as Korben Dallas as Leelo, an unexpected pair of heroes. Written and directed by Luc Besson, The Fifth Element is a fun and campy thriller with plenty of twists and turns to keep the audience on their toes. Though critical reception was somewhat mixed because of the heavily stylized futuristic world of the film, The Fifth Element has enjoyed a rich legacy.

Though there were some loose plans for a follow-up project, The Fifth Element was a massive undertaking, from the intricate sets and costumes to the sprawling story. Unfortunately, a sequel to The Fifth Element likely failed because the movie's box office performance didn't justify the continuous investment (via Movieweb). While we'll likely always be left waiting for this sci-fi adventure sequel, at least we have the original to enjoy for years to come.