There aren't too many movies that necessitate sequels. Unless a movie is part of a pre-proposed series or is an adaptation of a series of books, it should probably be able to stand alone. But a lot of sequels come from movies that are perfect by themselves -- sometimes the sequels compliment nicely; sometimes they are easily ignored; occasionally they actually take away from the previously regarded original.
It isn't often that a movie screams out for a sequel, but I think I've come up with seven that at least whisper a request for one. Two actually have source sequels that they would be adapted from. One has a lot of history to mine material from. Three of them have been discussed at length at different points in time by makers of the original(s). The problem is that none of these sequels is likely to ever grace your DVD player let alone your local theater. For whatever reason, they simply have too much against them in the minds of studio execs. For now, though, we can dream.
1. The Restaurant at the End of the Universe (sequel to The Hitchhiker's Guide to the Galaxy)
Even with the incredible cast and the surprisingly faithful-enough script, The Hitchhiker's Guide to the Galaxy was not the epic that I was hoping for. It also wasn't the blockbuster that Disney was hoping for. The filmmakers, Garth Jennings and Nick Goldsmith (aka Hammer and Tongs) and the necessary actors had signed on for the sequel, to be adapted from Adam's follow-up, The Restaurant at the End of the Universe, but it appears to be dead in the water. Despite my few reservations with the first film, I would love to see the sequel, as well as the rest of the series (they could end before The Salmon of Doubt, I guess). I remember being bored with some of the prehistoric Earth sequences in Restaurant, but I think they'd make for great cinema. In any event, I think Martin Freeman and Mos Def were a great duo in the original, and they alone should have been propelled to stardom following its release. Maybe they can appear in something else together.
2. Mathilda: The Next Professional (sequel to Léon -- aka The Professional)
I'm not sure if I'd really want to see Natalie Portman in action, but it has always been a curiosity of mine to wonder what happens to her character after Luc Besson's original film, which she debuted in when she was 12. Since that time she's gone and stunk up the Star Wars prequels and V for Vendetta and I'm not even sure if Besson, master of the female action picture could make me believe her as an assassin. Last year Besson squashed rumors that a sequel was in the works, but admitted if there was going to be one, he'd write it. The only way I see the thing ever existing is if Sony offers Besson a huge pile of cash, which they'd only do if Portman was really interested and was really able to sell tickets. Actually, I don't know why Sony hasn't already tried to make it happen. Anyway, while we wait (probably forever), Focus Features is currently working on a"reverse spin" on the film -- unconnected, however, from the original -- that we could possibly pretend is the sequel we're desiring.
3. Heathers Too (sequel to Heathers)
There are a few teen movies from the 1980s that have been tossed around as being sequel-worthy, including Ferris Bueller's Day Off, The Goonies (not as much a teen movie, I know, but close) Sixteen Candles and The Breakfast Club. But the only one that made any sense to me has been Heathers. From what I remember, it was to involve Winona Ryder's Veronica all grown up and working in some kind of office. And in that office she had to deal with a whole new group of Heathers. The genius of the idea is the satire of workplace cliques and politics, which often seem little different than the social structure of high school. The thing is, it would probably seem forced, and I'm sure there are plenty of office spaces that don't function enough in that way to allow people to get the joke. Then there is the issue of Heathers screenwriter Daniel Waters, who hasn't ever shown that he can still write juicy dialogue like that in his debut. Last year Ryder told Entertainment Weekly that the sequel was on, that it was set in Washington and that Christian Slater was making an appearance, but that it was still a ways away. I guess it isn't completely a dead idea yet, but I still wouldn't bet on it ever motoring to the multiplex.
4. LXG2: The Pirate's Conference (sequel to The League of Extraordinary Gentlemen)
I'll admit it: I enjoyed The League of Extraordinary Gentlemen. I thought it was a terrible movie, but I love the concept enough to get into the nonsense. Of course, few agree with me and the movie was a huge failure. It may have even caused Sean Connery to retire. Anyway, I think it could work if given a lot more attention and a lot more brains and a sequel might not be a bad idea. Other comic book adaptations have been improved with a second installment, such as X2 and Spider-Man 2, so why not LXG2? It could at least be a direct-to-DVD title. Although the original characters would be welcome for a sequel, without Connery around I'd prefer someone worked with some of the other Leagues that Alan Moore has come up with but not actually elaborated upon. And since pirates are so hot right now, I'd personally pick The Pirate's Conference, which includes Captain Hook, Long John Silver, Captain Blood and others. Since Moore has parted ways with DC Comics, some other film studio besides Warner Bros, which made the original, could probably snatch the rights away.
5. History of the World: Part II (sequel to History of the World: Part I)
I know, the joke of the title is that there is no sequel to the film. But that doesn't mean I can't want one. Thanks to Mel Brooks and the Monty Python gang, there have been some great historical satires, but there hasn't been one in a long time. David Wain's The Ten might be close, but simply won't be the same. The other reason there was no reason for a sequel to History is because the original was mostly a parody of biblical epics. What would Part II have to lampoon? Maybe if it was fast-forwarded there could be some ripe humor made out of the modern era -- and has there ever been a good WWII movie parody? While on the subject of Brooks, it is also important to bring up the idea of the Spaceballs sequel, which was joked about in the original (Spaceballs 2: The Search for More Money). It would be great if Brooks could give us some Spaceballs prequels showing Dark Helmet's origins as a spoof of the Star Wars prequels, but Lucas's films are already parodies of themselves. Anyway, there is a new Spaceballs animated series on the way.
6. Alien 5 (sequel to Alien)
The series should probably be left alone, but I've always been a fan of the entire franchise, including the third and fourth installments, and I wouldn't mind seeing more. It is certainly true that Alien³ and Alien: Resurrection aren't nearly as good as Alien and Aliens, but they continued the series' idea of each film having a different theme and style. Bad scripts aside, the last two films looked really great, and their directors, David Fincher and Jean-Pierre Jeunet, respectively, did the best they could with the material given to them. I think more young, stylish filmmakers could really do some cool things with the creatures, whether Sigourney Weaver was involved or not. Unfortunately, Fox has probably ended all hope for further sequels now that it is more interested in the awful-all-around Alien vs. Predator spin-off franchise. Apparently James Cameron had been working on a fifth Alien script until he heard about AVP, which he thought would kill the series, but the Aliens director has since stated that he liked the first AVP, placing it in his top 3 of all the Alien films.
7. Hoop Dreams Revisited (sequel to Hoop Dreams)
Ever since I got into Michael Apted's Up series of documentaries, I have wished that all my favorite doc subjects could be revisited every seven years. However, no two subjects have made an imprint in my memory as much as high school basketballers William Gates and Arthur Agee from Steve James' Hoop Dreams. Where are they now? What are they doing? Fortunately we have tools like Wikipedia to help us read up on people like Gates and Agee, but it would still be interesting to see their adult lives brought before the camera as they reflect on the hoop dreams of their pasts. There are countless other documentaries that I would love to play catch-up with, too. Unfortunately, the only doc sequel that I see on the horizon is Michael Moore's Fahrenheit 9/11½, which is due next year.
Bonus: Another good suggestion is Roger Rabbit 2, which was recently mentioned in Jette's Cinematical Seven: Films We'll Never Get to Watch.