10 Horror Movie Plot Twists That Were Totally Pointless

My Bloody Valentine, a solid if formulaic '80s slasher, unfolds in a Canadian mining town still haunted by the crimes of Harry Warden. The mine's supervisors neglected their duties to go to a Valentine's dance, and Harry, the sole survivor, later went insane and killed the neglectful employees, before warning the town not to host any more Valentine's dances or he'll kill again. 

Inevitably, the town goes ahead with one 20 years later, and a murderer in mining gear starts going around and slaughtering people with a pickaxe. It would appear that Harry has escaped from the asylum... but no. It's actually Axel (Neil Affleck), one of the film's many partying youngsters. A clumsily deployed flashback reveals he was the son of one of the original killer's victims, and the trauma has driven him to become a copycat. 

Twists about a slasher villain's identity can work if done well. In this case, it was much better just to leave things as they were. The movie had already done well in building up Harry Warden as a villain, and to negate all of that build-up in the final five minutes was not the right way to go, especially as there hadn't been any sort of hint towards Axel's backstory. 

Ironically, the rather weak 2009 My Bloody Valentine remake did actually provide a better plot twist. As for the original, it's honestly one of the better Halloween rip-offs, but the pointless twist came dangerously close to undoing all that good work.