11. Blade Runner
Blade Runner is Ridley Scott's dark futuristic masterpiece. But it had a famously troubled journey to get there which can be seen with the original theatrical cut. After investors found the film too dark and confusing this version was saddled with a voice-over from Harrison Ford where he explains everything to the audience.
Ford sounds so bored performing it that he might actually be in physical pain, while the VO has the negative effect of taking the movie's subtext and turning it into actual spoken text.
The other infamous addition was the happy ending. Pieced together using outtakes from opening of The Shining, the reshot conclusion sees Deckard and Rachel drive off together into a sunny future. Deckard reveals that Rachel has no termination date so they're set to live happily ever after. The End.
The tone of this scene is in complete contrast to the movie preceding it and it was - alongside the bad voice-over - completely removed from all subsequent re-edits.