I Know What You Did Last Summer originally featured a really lame ending - here's why the director purposefully did a poor job on it. Horror movies were in something of a bad spot during the early 1990s, with both audiences and studios mostly shying away from the genre. It wasn't until Scream came along in 1996 that it got a major shot in the arm, with Wes Craven's iconic slasher adding a meta touch that gave the movie a reinvigorating freshness.
This naturally led to a string of sequels and copycats, including the likes of meta-horror flicks such as Urban Legend or The Faculty. Screenwriter Kevin Williamson was extremely prolific during this period, penning the first two Scream movies, The Faculty and acting as producer and uncredited writer on Halloween H20. He also penned the script for 1997's I Know What You Did Last Summer, though it lacks the meta touch of much of Williamson's other 1990s work.
I Know What You Did Last Summer cast Jennifer Love Hewitt as lead Julie James, with then up and comers like Freddie Prinze Jr., Ryan Phillippe and Sarah Michelle Gellar rounding out the protagonists. The story opens with Julie and her friends accidentally hitting a pedestrian during a night out, but rather than report it and jeopardize their futures, they dump the body and pretend it didn't happen. A year later they're stalked by a killer with a hook who somehow knows what they did, and who wants to make them pay. The movie was loosely based on the 1973 novel of the same name and was a big hit back upon release.
I Know What You Did Last Summer now ends on a solid jump scare which takes place a year after Julie and Ray (Freddie Prinze Jr.) seemingly kill their stalker. She enters a shower to see the words "I Still Know" written on a mirror in steam before the Fisherman jumps through the glass and it cuts to credits as she screams. This wasn't the original ending, with director Jim Gillespie revealing to Digital Spy back in 2017 that the first ending saw Julie in college receiving a spooky email stating "I Still Know" instead.
The director admitted he hated filming this finale and shot it in the dullest possible manner, knowing the studio would ask him to film a better one later on. His ploy worked, as I Know What You Did Last Summer test audiences dug the movie up until this weaksauce ending. Sony realized they likely had a hit, and thus Gillespie was allowed to film his preferred ending. Two sequels followed the movie, but after a planned movie reboot - which The Haunting Of Hill House's Mike Flanagan co-wrote a screenplay for - failed to launch, I Know What You Did Last Summer will soon be revived as a TV series on Amazon.