Many icons, houses, scarezones, and event concepts have been scrapped over the years.
- Many Icon concepts are gone through before Universal A&D finalizes the Icon to be used for the event. Most of these are lost to the archives but some of them eventually get used in some way, shape, or form. For example, Jack's girlfriend Chance was derived from a scrapped Icon, his's ex-girlfriend Jill, of an abandoned event that would span both the main park and Islands of Adventure. Lady Luck had her origins in an earlier Icon concept as well, known as Fate (who was originally planned for the 2005 event as well).
- 2001's intended Icon, Eddie, was a chainsaw-wielding horror movie addict changed into Jack's brother then dumped completely due to the 9/11 attacks. Eddie would reappear with other Icons in the Horror Night Nightmares house in 2004 and in the Horror Nights: The Hallow'd Past house & Fear Revealed scarezone in 2010. He received his own house, RUN: Hostile Territory (a sequel to the 2001 house RUN he was originally supposed to appear in) in 2006. The original RUN was intended to be his house before he was scrapped from the toned-down event. In his original incarnation as Edgar Sawyer, he would have pulled a Hostile Show Takeover and killed Jack in the Opening Scaremonies
. Whether Jack would have stayed dead is another story with how many times Edgar had to try before it stuck. - 2002's Islands of Fear event was originally going to be even more elaborate than what the ultimate final product turned out as:
- It would've had the park's rides be changed to reflect the theme of their respective scare zones. For instance, Island Under Siege (Marvel Superhero Island) would have had a Marvel supervillains theme where The Incredible Hulk Coaster would've been themed to the Green Goblin, Storm Force Accelatron would've been themed to the Kingpin and had heavy metal music playing, and Doctor Doom's Fearfall would have sound effects of blood-curdling screams added to the ride. At JP Extinction, (Jurassic Park) the River Adventure would've had extra effects added to make the ride scarier, along with having scareactors at the ride's exit. Finally, at Island of Evil Souls (Lost Continent) there would have been scareactors in the queue lines for Dueling Dragons and The Flying Unicorn, and the vehicles of the latter ride would've been facing backwards. Dueling Dragons wound up having an homage haunted house for the 2023 event so in a roundabout way, it did get its scareactors after all.
- Cindy was intended to be the mascot, but was replaced by The Caretaker after a rash of child kidnappings case. She had a cameo in Scream House: Resurrection in 2006 and her own house, The Orfanage: Ashes to Ashes in 2010. However, Universal was considering having her be the icon for the 2010 event and aren't against the idea of having her as an icon in the future.
- A haunted house for The Thing (1982) was originally going to be at this event for its 20th anniversary, but fell through due to budget cuts. It did ultimately come to life five years later at 2007's event.
- The original finale for the Project Evilution house would've included a giant Tyrannosaurus puppet.
- Early drafts of the event included there being another comedy show inside the Sinbad theater.
- At one point, there would have been a big nighttime show on the lagoon called Danse Macabre.
- Concepts for an "extreme house" (a house in which, with full permission, visitors would be taken through more intense scares and scareactors would be allowed to break the cardinal rule: no touching the guests!) have been brought up for the Orlando event for quite some time. The most concrete example of this was the Severe Fear house for HHN 13 that was scrapped at the very last minute due to fear that someone might get injured and sue the park. The full treatment and construction documents can be found here. Elements from this house treatment (the door scene, the use of live flame in a house, a chainsaw wielding drill sergeant, etc.) would be reused in future houses and scarezones.
- One of the ideas for the event in 2000 involved giving E.T. Adventure a twisted makeover that would've been dubbed "I.T.: Interstellar Terror". The differences in the attraction would've started off in the ride's queue line, where scareactors would be positioned throughout the forest to scare guests. From there, the actual ride would start off normally... until the riders reached the Green Planet, where all of the animatronics of E.T.'s friends would have been taken out and replaced with scareactors dressed as gruesome-looking aliens. The ride then would've ended with the last E.T. animatronic being replaced with Jack the Clown jumping out for one last scare. Steven Spielberg balked at the whole idea, which killed the proposed makeover dead in its tracks.
- Early plans for 2003 had the icon being an evil Walt Disney-inspired animator that would've unleashed his creations upon the different islands, but in the end, A&D decided to take that year's icon into a different direction.
- 2005's "Blood Ruins" house was originally going to be located inside the queue line for Dueling Dragons, but ended up getting moved to one of the soundstages. That same year, there were also plans for there to be an eighth house that would've carried a voodoo-type theme.
- A scarezone for Army of Darkness was in the works for 2009's event, but cut and replaced with Lights, Camera, Hacktion due to Universal not being able to secure the license for it. A scene for the film was still sneaked into the Silver Screams house from that same year, however (via the Captain Ersatz method).
- 2004 originally would've featured an icon called "Dr. Payne", who also would've been involved in the Disorientorium house.
- Earlier plans for 2001 had it being a two-park event and being about Jack going up against a modern biker-gang sort of guy. Another idea is that Eddie would've been Jack all along, and that Jack merely would've been a mask on him that he would rip off.
- One concept for the Sweet 16 year had a scare zone that would've been located in "The Boneyard" and would've themed around Jack's "extended clown family". Another concept would've had there being a giant birthday cake prop with candles that would shoot fireworks off into the sky.
- Supposedly, the 2012 house Gothic, set in a medieval cathedral filled with menacing gargoyles, is based on a canceled room concept for an old house.
- Many of the masks worn by the Beasts in 2012 were based on the masks of older characters, but several of them were a more unique design. Rumor has it that these masks were part of a canceled house based on the Chupacabra.
- There were initially plans to have 2012's event return to being in both parks due to the construction for Diagon Alley and Transformers: The Ride going on at the time, but the plans were ultimately scrapped.
- An American Werewolf in London was set to be a house in two previous years, believed to be 2008 and 2012, and came close enough to completion that props and sets had to be scrapped or retooled. 2013 was when John Landis finally gave personal approval... and the positive reception to the house was enough for Landis to give approval again for the houses' return in 2015.
- 2008's house Creatures! was a fun, campy house inspired by EC Comics. Set in a Southern roadhouse called the Butchered Buck, the house chronicled the battle between a group of rednecks and goofy-yet-scary aliens◊. That's all well and good. The problem? The alien costumes were too large and cumbersome and were deemed to be a safety hazard shortly before the event begun. With the exception of one creature seen behind a fence, there were nearly no creatures in the house called "Creatures".
- American Horror Story was one of the planned IPs for 2013, but due to creative conflicts with the show's owners, it was scrapped and replaced with an Evil Dead (2013) house. It wouldn't be until 2016 that the show finally got its own house.
- 2013 was going to have scarezones with a forest-type theme to tie into the "What Evil Has Taken Root?" theme that was being marketed. It ended up getting replaced when marketing insisted on having the scarezones all be themed around The Walking Dead.
- 2014 would've had an icon called the "Prop Master" that was cut for reasons unknown.
- A Scream (1996) house almost made it into 2015's event, to the point that the house had already been fully constructed, leaked early marketing materials listed it as a marquee attraction, and an alternate version of the commercial for the event that included Ghostface had been filmed (though never aired). Things fell apart due to serious creative disagreements between Universal and The Weinstein Company, the short version being that the Weinsteins wanted the house to be based on the MTV reboot series while Universal's Art & Design department wanted to base it on the original movie. This led to the house being scrapped (with the scareactors getting less than two weeks' warning before rehearsals) and converted into a house based on The Purge. Numerous aspects of the planned Scream house were still very noticeable in the final product.
- Jack Presents: 25 Years of Monsters and Mayhem was originally going to feature scenes from 2010's Catacombs and 2011's Nevermore: The Madness of Poe houses, but both wounded up being cut from the budget.
- A third "Sprung Tent" was to be constructed in 2015 for the ninth house; but due to budget, creatives ultimately opted to use one of the Shrek 4D theaters for the house instead. It later would be built in 2016, next to the queue line for Men in Black: Alien Attack; as the loss of the Disaster! queue line meant that a new house location needed to be added.
- A house based on the films of Alfred Hitchcock has been proposed multiple times in the past, but has yet to materialize.
- A house based on H. P. Lovecraft's works has been in Development Hell for a while.
- The Caretaker was intended to return as an Icon for 2017, but after the mixed reception of Chance, the event's marketing department didn't feel comfortable about using any Icons outside of Jack.
- Two characters called "Blood" and "Bone" were intended to serve as the mascots of 2017's event, but due to a mixture of budget issues and creative disputes, only the latter came to be.
- 2017's event was going to have a house based on The Conjuring, but it was dropped due to a variety of legal issues. At Orlando's event, it was replaced with the Hive house, while at Hollywood's event it was made into the Titans of Terror Maze.
- 2017's The Horrors of Blumhouse initially was going to have a scene for Ouija, but it was cut at the last minute due to Hasbro refusing to license the property for a haunted house. Eerily similar to what happened with Scream in 2015, the scenes were given merely minor redecorations and made into scenes from The Purge. For Orlando's event, the house altogether was originally going to be based on just Insidious, but Executive Meddling resulted in it being changed to feature other Blumhouse productions. Insidious still took up most of the house, though.
- A Beetlejuice show was proposed for 2018's event as a replacement for Bill & Ted's Excellent Halloween Adventure, but it was dropped in favor of using the budget to add a tenth house to the event.
- Rumor has it that the event's team once tried to pitch the idea of a Game of Thrones house, but did not achieve any success.
- 2020's event was planned to feature a Billie Eilish house. When the event was cancelled, Eilish's agents declined to allow the attraction to return in 2021, believed to be because Eilish's music was moving in a Lighter and Softer direction with her 2021 New Sound Album Happier Than Ever, and featuring a house based on the preceding album WHEN WE ALL FALL ASLEEP, WHERE DO WE GO? would've conflicted with that.
- 2021's Revenge of the Tooth Fairy was intended to run in the 2019 event, but it was held back after executives were able to successfully negotiate for an Us house that took its spot that year.
- 2022 was slated to have a house based on Evil Dead, likely as a tie-in to Evil Dead Rise. That film's delay to April 2023 was probably responsible for its house being cancelled in Orlando and pushed back to the 2023 event in Hollywood. The Orlando Evil Dead house was redecorated and became Hellblock Horror; the latter's "prison for extradimensional monsters" concept came about because of the need to develop it in a relatively short period of time, allowing for a heavy reuse of past monster costumes.
