Sequels are big business in Hollywood and beyond, and sometimes a follow-up is put into production before the first movie has even hit theaters.

Earlier this year, Ti West's X was released to strong reviews and fan reactions, with many praising it as a throwback to old school slashers while still putting a fresh spin on the genre. After such a suspenseful ride of a horror movie, uninitiated viewers were probably surprised to see the post-credits teaser for Pearl, a prequel that West and crew shot back-to-back with X.

While a typical sequel may take a few years to make it to theaters, occasionally a studio will have such a confidence in a franchise that they give one the green light simultaneously at the same time as its predecessor. Some of the most successful movies of all time have followed this model, especially when a continuation is absolutely necessary to the story.

Alexandre Dumas' The Three Musketeers has had quite a few film adaptations over the years, but one of the more underrated is the two-part version directed by Richard Lester. While it was shot as one movie, the fact that it would've run well over three hours prompted 20th Century Fox to split it in two for its theatrical release.

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While it's fairly obscure today, The Four Musketeers is an entertaining adventure that continues the fun, light tone set by the first film, and wraps up D'Artagnan's story with a triumphant conclusion. It also boats a terrific cast, featuring such names as Michael York, Oliver Reed, Faye Dunaway, and Christopher Lee.

The 1978 Superman was a huge hit with both critics and audiences, laying the groundwork for the modern superhero genre and making director Richard Donner a Hollywood darling. Although a sequel starring Christopher Reeve's iconic Man of Steel was probably inevitable, executive producers Alexander and Ilya Salkind put Superman II into production just after the original wrapped.

Interestingly, the Superman films were not the first time the Salkinds had dealt with back-to-back sequels, with the duo having previously worked on The Three Musketeers duology. In fact, they brought in Musketeers director Richard Lester to reshoot most of the movie after Donner was fired.

Shocking as it may be for a movie as popular as Back to the Future, Robert Zemeckis initially had no plans for sequels, but the film's runaway success meant that sequels were begging to happen. But rather than settling for just one, Zemeckis and Universal went for broke and shot two sequels back-to-back.

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That gamble paid off, with both movies being hits, and Back to the Future Part III is seen by many fans as the better of the two. It certainly reinvents the franchise's wheel with a Western setting, and has plenty of memorable set-pieces and quotable lines, especially Doc's heartfelt goodbye to Marty in the final scene.

Many believed that J.R.R. Tolkien's epic saga was impossible to effectively translate to film, but Peter Jackson's The Lord of the Rings trilogy proved to be instant classics that redefined fantasy cinema. All three movies were hugely acclaimed and broke numerous box office records, and they still rank very high on sites like IMDb's best of all time lists.

The Fellowship of the Ring may have been a terrific start to the trilogy, but The Two Towers proved that its predecessor was no fluke, expanding the story's scope and scale to give it a truly epic feel. It's also gives a proper introduction to Sméagol/Gollum, one of the trilogy's most iconic characters.

The Matrix is one of the ultimate lightning in a bottle movies, a fresh take on the cyberpunk genre that's both very much of its time and oddly timeless. Hoping to continue Neo's story, the Wachowskis quickly got to work on making a trilogy, with two sequels filmed concurrently.

While The Matrix Reloaded received decent reviews and a strong box office take, Revolutions was critically derided and was much less financially successful. Many fans found it to be an anticlimactic conclusion, with Neo brokering a peace between humans and machines after meeting a literal "Deus ex Machina".

Quentin Tarantino's martial arts revenge saga Kill Bill is an excellent action movie, but its over four hour runtime leaves viewers feeling like they've watched a legitimate epic. Naturally, a movie of that length would've been a hard sell theatrically, so fans got to see the Bride's story wrap up seven months after Volume 1.

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While Volume 2 isn't as action packed as the first film, it's still a very entertaining journey through Tarantino's unique world, and when the action ramps up, it's excellent. The fight between Beatrix and Elle Driver rivals many of Volume 1's battles, being vicious and intimate in a way that the previous ones were not.

After Pirates of the Caribbean: The Curse of the Black Pearl was an unexpected hit for Disney, fans were clamoring for the further adventures of Jack Sparrow. Thinking practically, Disney greenlit two back-to-back sequels, allowing screenwriters Ted Elliott and Terry Rossio to craft an epic trilogy.

The third film, At World's End, continues the trend of Davy Jones being a villain that fans can root for, but captain of the Flying Dutchman's likability may have left the protagonists out to dry. The movie received mixed reviews despite grossing close to a billion dollars, with many criticizing the convoluted plot and excessive length.

With a thrilling plotline and memorable characters, Stieg Larsson's Millenium series was ripe for a big screen adaptation. Unlike David Fincher's The Girl with the Dragon Tattoo, the original Swedish version had the two sequels produced back-to-back, with The Girl Who Kicked the Hornets' Nest closing out the trilogy.

While the first movie was a critically acclaimed international hit, neither sequel could match those heights, with Hornets' Nest in particular getting mixed reactions. Still, Noomi Rapace and Mikael Nyqvist give great performances, and Lizbeth Salander gets plenty of badass moments, particularly in the climax.

The Harry Potter films were a worldwide phenomenon beloved by fans, but the team at Warner Brothers needed to stick the landing in order to fully cement their classic status. In order to effectively adapt series finale Deathly Hallows, splitting the book into two movies was the best choice, allowing screenwriter Steve Kloves to hit all the essential plot points and give closure to the major character arcs.

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Both volumes were wildly successful, especially Deathly Hallows - Part 2, with Harry's big showdown with Voldemort being incredibly satisfying to watch after such a big build-up. It's also notable for kicking off a trend of book series adaptations ending with two-parters, none of which could quite match Deathly Hallows' standard.

As arguably the biggest film franchise of the Marvel Cinematic Universe, an epic two-part finale to the Infinity Saga made all the sense in the world, so the Marvel brain trust produced Infinity War and Endgame at the same time. Both films received very positive reactions from critics and fans, with the latter going on to become the highest-grossing movie of all time.

Endgame's spectacle is obviously a joy to watch, and it's fun to see so many fan favorite heroes teaming up to fight Thanos. But it's the character arcs that make the movie truly great, especially seeing Tony Stark and Steve Rogers' stories come to a bittersweet close.

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Pierce Brenner is a freelance list writer for Screen Rant. He graduated from California State University, San Marcos in 2019 with a BA in History, with a minor in Film/Video Production. Pierce's childhood love of Disney, Pixar, and Star Wars sent on him the path to movie fandom early, but it was The Lord of the Rings trilogy that inspired him to become a filmmaker. His love for film knows no bounds, and he'll watch anything from prestige epics to 70s/80s exploitation. Currently writing a script for a horror-thriller feature.