Few movie franchises from any genre - let alone horror - can keep going by simply doing the exact same thing over and over again. At some point, something has to change, and more often than not this ends up being a focal character.
It goes without saying that people change over time - take Luke Skywalker in the Star Wars sequel trilogy, for example. But sometimes filmmakers re-jig a character's personality in such a sudden way that it seems jarring and unconvincing.
And this is perhaps more common in horror than any other genre, where producers and filmmakers appreciate the appeal of fine-tuning their evergreen characters in the pursuit of ongoing box office bucks across eight, nine, or even ten movies.
Whether heroes, villains, or more ambiguous tweeners, these 10 horror movie characters all underwent shocking personality transplants between movies.
Perhaps they suddenly developed a sense of humour, had their IQ conveniently drop 50 points, or simply betrayed their established character from previous films.
In some cases it thoroughly pissed the fanbase off, while in others it was an inspired enough change to basically work. Either way, these personality shifts weren't subtle in the slightest...
10. Leatherface - The Texas Chainsaw Massacre 2
The original Texas Chainsaw Massacre depicted its chainsaw-wielding antagonist Leatherface (Gunnar Hansen) as a terrifyingly animalistic, mostly one-dimensional blunt object - a mentally disabled man who kills as instructed to by his family.
But The Texas Chainsaw Massacre 2 is a considerably campier affair - effectively a not-so-thinly-veiled parody of the original movie which presents Leatherface (now played by Bill Johnson) quite differently.
In short, the sequel gives us the horny Leatherface none of us ever expected.
Here he is hopelessly enamoured with human protagonist Stretch (Caroline Williams) and even thrusts his chainsaw around as a substitute penis, because why the hell not?
Some fans argue that this is simply a case of the emotionally stunted Leatherface going through some belated personal development, but the lovesick puppy depicted here is nevertheless a far cry from the ferocious, no-nonsense Leatherface encountered in the first film.
There's no denying The Texas Chainsaw Massacre 2's stature as a cult classic, even if for many who loved the original it turned Leatherface into too much of a joke.