10 Horror Movies That Made It Up As They Went Along (But Were Awesome Anyway)

10. Friday The 13th

Friday the 13th concludes with our heroine, Alice, discovering Mrs. Voorhees was behind the killings in Camp Crystal Lake. After she decapitates Mrs. Voorhees, Alice takes a canoe out to the lake.

But while Alice reflects on everything she's just endured, the decomposing corpse of Mrs Voorhees' son, Jason, springs from the waters and grabs her. Despite the fact this moment is revealed to be a dream, it was the scene that got everybody talking, which inspired the studio to release a sequel.

Although "gotcha" endings are quite common with slashers, Friday the 13th's climax was an afterthought. After Alice killed Mrs. Voorhees, the movie was meant to abruptly end.

But one of the film's higher-ups (it's never been confirmed who) convinced the director to incorporate this jump scare at the end.

Even though Friday the 13th only had one major last-minute change, it's worth mentioning since it was the best scare in the movie. Also, Friday the 13th probably would've never turned into a franchise if this stinger wasn't added in. If that was the case, the hockey mask wearing brute, Jason Voorhees, probably would've never become a horror icon.