Buffy season one's first episode starts with Buffy the slayer coming into the town of Sunnydale, and she is already a slayer having fought vampires in LA.
So this first episode isn't really an origin-story. But there was once a movie in 1992 about Buffy, where she is played by another actor (Kristy Swanson), and that was an origin story. Joss Whedon wrote the story, but the studio filmed it with another director and the story was turned into a light comedy.
It's not a good movie, it's corny, and there is very little of what made the tv-show great, very little underlying drama, too little chemistry, and there were no scoobies, and too much focus on comedy (and it lacked the idea that vampires would just burst into dust when being killed by the slayer, yeah a small thing, but effective in selling the idea that vampires are different to humans and that they really died)... but nonetheless I like it, it's a sort of guilty pleasure.
I like Swanson playing Buffy, not only her more pronounced physicality, that seems more fitting for a slayer (though Gellar clearly conquers the role nonetheless). And I like the whole introduction between the watcher and Buffy before she accepted what he said, and the training-sequence is good...
I just view it as a sort of "wacked" pilot to the tv-show, since we didn't see Buffy's first actions in LA as a slayer (except for the few scenes in "Becoming").
I'm thinking about editing the movie, to bring it more in line with the tv-show, removing the idea of the reincarnating watcher, removing all the cringe worthy aspects, for example removing the idea that the slayer has menstrual cramps as warning when vampires are nearby (yes, that was part of the movie, lol!), making the fights more dynamic, adding the sound of vampires turning into dust (and not showing them laying around after being killed), adding two dialogue-instances from the tv-show (audio only to add some needed drama)...
It probably won't turn a bad movie into a masterpiece, but I think it could be made much more acceptable, a sort of real pilot for the tv-show. What do you think?