Making multiple films together. Normally Hollywood waits until it knows it's got a hit before ordering up a sequel, but that approach has problems. If they're lucky, the original writers will have left Sequel Hooks, but the seams will still be visible, and they've got to get the original cast back together.
It's so much simpler to make the sequel before the first film is released. The stories can be written to fit together smoothly, and none of the cast are going to disappear, or demand more money.
Movie multipacks come in three varieties.
Two sequels for the price of one. Following a hit film with a two-pack of sequels, to complete the trilogy. Examples:
- Back to the Future
- The Matrix
- Pirates of the Caribbean (before the Trilogy Creep set in)
- Star Wars
- Avatar is going Up to Eleven with four concurrently filmed sequels, creating a Two-part Pentalogy.
One story in N parts. When the story is too long to fit in just one part it can be split over several films, all but the last typically ending in a Cliffhanger. Examples:
- The Three Musketeers (1973) (even though this version was shot as one film, it was eventually released as two. This resulted in its director (Richard Lester) getting sued by some of its cast, who had only been paid for one film and felt they should have been paid for two.)
- Kill Bill
- Superman; written as a 5-hour epic, shot as two movies, though the second was mostly reshot after its director (Richard Donner) was fired.
- Death Note
- The Lord of the Rings and The Hobbit
- Avengers: Infinity War and Avengers: Endgame form a two-part story that caps off the entire Marvel Cinematic Universe up to that point, with the first movie ending on a major cliffhanger. They were originally marketed as Infinity War: Parts One and Two before being given separate titles to avoid the impression of this trope.
- Justice League (2017) was initially intended to be shot in this way, but was released as a single film that doesn't count as this trope outside the larger scope of the DC Extended Universe. That being said, the Director's Cut, Zack Snyder's Justice League, is four hours long, giving much credence to previous rumors that the amount of material that was filmed by the original director was enough to fill two films.
String of stories. Particularly with book adaptations, the story may naturally come as a multi-volume epic. Each individual film has closure, not a cliffhanger, but together they form a greater whole. Some adaptations have also been subjected to the above One story in N parts phenomenon by splitting the final book into two films, essentially doubling down on this trope. Examples:
- Harry Potter
- The Hunger Games
- Divergent. In this case, adapting the final book Allegiant into two films resulted in disaster when the first part flopped at the box office. Lionsgate intended to produce Ascendant as a TV movie and/or miniseries to resolve the cliffhanger, but lead actress Shailene Woodley dropped out as it wasn't what she was hired to do, and the plans were ultimately cancelled.
- It (2017) and It: Chapter Two; the novel alternates between two time periods, which the films divide into two mostly distinct movies.
All the varieties are often sold as Boxed Sets.
In the case of film adapting books, this can lead to Divided for Adaptation.