Sequels are a tricky business. Every time Hollywood hits it big with a movie that draws the crowds and piles up the box office receipts, you know that someone somewhere is discussing the possibility of them doing it all over again.
It's easy to be cynical about this, but for fans there's often a great deal of joy to be taken from this. If a movie gives us endearing characters, plenty of action and spectacle, and leaves the story just that bit open enough at the end, then why not do keep it going? More entertainment for us, more money for them: win-win.
The problem is, once any franchise is a few films in, there are invariably differences of opinion as to where they should go next. Sometimes they run short of ideas; sometimes they just have too many ideas to choose from. And sometimes, as we'll see, the ideas they come up with are just that bit too bananas.
Whatever happens, any ongoing movie series is going to have left a few sequel ideas abandoned along the way; and in some instances, hindsight tells us that the sequels which got left behind may very well have been a whole lot more satisfactory than the sequels which ended up getting made.
10. James Bond Of The Secret Service, AKA Warhead
By the mid-1970s, the James Bond franchise was a seemingly unstoppable juggernaut. With Roger Moore in the role, it took on a whole new lease of life, reaching previously unseen heights of absurdity.
However, as mad as the Moore movies may be, that's nothing compared to what might have been with unmade 007 movie 'James Bond of the Secret Service', or 'Warhead'.
As older fans may be aware, there was a long-running legal battle over the rights to Bond between Cubby Broccoli's Eon Productions, and Kevin McClory, independent producer partially responsible for 1965's Thunderball.
Long story short, in 1975 McClory was legally able to produce his own Bond movie outside of the established series, and he'd even managed to persuade original 007 actor Sean Connery to star.
Warhead's eye-opening premise saw Bond's arch-nemesis Blofeld of SPECTRE stealing American and Russian bombers in the Bermuda triangle, then attaching their nuclear weapons to robot sharks which would be sent to attack New York City.
Yes - sharks with frickin' nukes on their heads. This isn't Austin Powers. This was a real 007 script.
Although Warhead collapsed, McClory and Connery would finally make their unofficial Bond movie in 1983's Never Say Never Again, an enjoyable but fairly prosaic retread of Thunderball.