It's the nature of movie making as a business for any even vaguely successful project rapidly to be considered for its franchise potential. It doesn't matter if the story ended pretty conclusively with the world saved and the hero dead after a noble sacrifice, once those millions start rolling in the studio suits will start thinking "sequel?"
Often it is only the objection of the original movie's star that prevents some truly terrible sequel concepts from coming to fruition.
The Se7en sequel, Ei8ht, in which Morgan Freeman's Detective Somerset developed psychic powers to track a new killer? Shot down by Freeman. The Forrest Gump follow-up in which Forrest hangs with Jenny's ghost, captures Saddam Hussein and brings down the Berlin Wall? Rejected by Tom Hanks as no longer relevant post-9/11.
There are, however, those rarer cases when it isn't the star that's holding the sequel back at all. In fact, the lead actor seems keen to throw themselves into returning to one of their signature roles with a truly bonkers new instalment and it's only the sheer weirdness of the pitch that is preventing a studio from committing to it too.
But, hey, if the stars are happy to commit themselves to such outlandish concepts as these ten crazy sequels, shouldn't we perhaps get a chance to see them?
10. Silver Surfer
Tim Story's two Fantastic Four movies earn their damning with the faintest of praise as "the best live action Fantastic Four" through playing it as safe as possible.
Story made Marvel's first family into a middle of the road action film, downplaying any of the weirder cosmic elements of the comic to keep the scope narrow and earthbound. He turned gargantuan planet devourer Galactus into a vaguely sinister cloud. A proposed spinoff, however, would have gone in a very different direction.
After doing the performance capture to portray the titular shiny board-rider in sequel Rise Of The Silver Surfer, star Doug Jones was excited to talk up the possibility of a solo movie for the cult favourite character. Jones, who spoke of his love of Norrin Rad at any opportunity, became even more keen on the project once Fox agreed to a pitch from Babylon 5 creator and sci-fi icon J. Michael Straczynski.
In contrast to its unambitious predecessors, Straczynski's Silver Surfer script would have fully embraced the outlandish weirdness of Marvel's cosmic universe, journeying to Radd's home world of Zenn-La to defend against a vengeful Galactus in a movie that Straczynski described as an adult sci-fi epic.
Fox instead went ahead with rebooting the Fantastic Four, although now that the rights have reverted to Marvel an MCU Silver Surfer movie is a distinct possibility. They could do worse than calling on Jones again, given his passion for the character.