1. While Sarah Michelle Gellar wound up in the starring role of care worker Karen Davis, it was her Cruel Intentions co-star Selma Blair who was first choice for the character. In fact, producer Sam Raimi, who shepherded the American remake of the Japanese films to screens, claimed he'd never seen Buffy the Vampire Slayer or any of Gellar's other films.
2. One of Gellar's biggest scenes in The Grudge takes place as Karen showers. Unfortunately, she found herself allergic to the water in Japan. To film the scene and protect the actress, all parts of her body not visible to the camera were wrapped in garbage bags.
3. After bringing the doomed Saeki family to life (and death) in both Japanese films, actors Takako Fuji, Takashi Matsuyama and Yuya Ozeki all appeared in The Grudge, reprising their roles of mom Kayako, dad Takeo and son Toshio, respectively.
4. While Toshio was almost never without his beloved black cat Mar, in real life, poor Yuya was terrified of cats.
5. Despite not sharing any scenes together, Jason Behr (who played Karen's ill-fated boyfriend Doug) and KaDee Strickland (who played Susan, whose brother moved into the home haunted by the Saeki family) met on set and began dating after discovering a shared interest in Japanese culture. They got married in 2006.
6. Of all the Japanese horror films remade for American audiences in the 2000s, a list that included The Ring, Dark Water, Pulse and One Missed Call, The Grudge was the only one to keep the story in Japan rather than moving the action Stateside.
7. Director Takashi Shimzu, who was eager to work on the remake of his original Japanese films, spoke no English and had to communicate with his cast via translators. He also provided the film with the ghastly open-mouth gasping sound the ghosts make.
8. The Grudge 2 was given the greenlight on the Monday following the first remake's release after the film proved to be a surprise success, grossing more than $39 million in just three days. With a production budget of less than $10 million, its worldwide total box office of over $187 million made it one of the most profitable movies of 2004.
9. While The Grudge was a remake of the first Japanese film, The Grudge 2 told its own unique story while also incorporating story elements from the first Japanese film that didn't make it into The Grudge.
10. As Karen's equally ill-fated sister Aubrey, Amber Tamblyn appeared in both of the most successful horror franchises based on Japanese films in the 2000s after having appeared in 2002's The Ring as well.
11. The Grudge 3 was the first film in either the Japanese or American franchises not to be directed by Takashi Shimizu, with Toby Wilkins taking over. Incidentally, it was also the first one not to receive a theatrical release and the first one not to employ the nonlinear sequence of events successfully used previously.
12. While each of the Grudge films featured a different actor as Toshio, The Grudge 3 marked the first time Takako Fuji wouldn't be playing Kayako as she'd grown tired of playing the ghost after nearly a decade in the role. She was replaced by Aiko Horiuchi.
13. When Scary Movie 4 spoofed The Grudge in 2006, the film had two actors from the franchise in its cast: Bill Pullman, who played the object of an obsessed Kayako's affection on the first film, and Beau Mirchoff, who starred in The Grudge 3 as Andy, boyfriend to new main character Lisa.
14. The upcoming 2020 revival, also entitled The Grudge, will be the first to have no involvement from Takashi Shimizu whatsoever. (He remained a producer on The Grudge 3.) Taking place concurrently with the 2004 timeline of the first film, The Grudge will take place in "a small town in suburban America" with a totally separate story, director and co-writer Nicolas Pesce told BloodyDisgusting.com in September.
15. While it hasn't happened in America (yet), Kayako (played by new actress Runa Endo) met her match in Japan in 2016 when she was pitted against Sadako Yamamura, the central antagonistic force from the The Ring franchise. (The character was renamed Samara for the American franchise.) The end result of Sadako vs. Kayako? They become a single entity, Sadakaya, of course.