It's no secret that movie sequels have been a source of tension in the entertainment industry; one has only to look as far as the Star Wars franchise to see the damaging effects a sequel can have on the original content, not to mention the coexistence of the fans. If there's anything we learned from The Phantom Menace, it's that bringing characters back for a second, third, or even fourth go-round can be a touchy subject. Ultimately it all comes down to a cautious optimism and sense of trust harbored by fans that takes a special kind of magic not to betray. Some sequels are able to capture that magic, a prime example being Spider-Man 2, but movies like Spider-Man 3 can leave franchises in a state of disrepair. Unfortunately, most sequels are made not for the enhancement of the original, but to snag over eager moviegoers - and their hard-earned dollar - by giving them what they want; a chance to see their favorite characters grace the screens once more. Admittedly, some sequels execute this concept extremely well, and have managed to become classics in their own right; the Back to the Future trilogy, Indiana Jones installments (sans Kingdom of the Crystal Skull), and Nolan's Batman Trilogy, to name a few. But there's a third breed of sequel that has us breathing a sigh of relief while simultaneously wondering if we've been robbed of a cinematic masterpiece. Over the years a number of sequels have been officially announced or considered, and yet were left by the wayside, offering nothing more than inspiration for your next piece of fanfiction. Here is a list of 10 sequels that were announced and just disappeared...