I might as well elaborate on the mass shooting iceberg I posted.
Italicized ones are often written in shorthand and will probably be elaborated on later when I figure out more definitively what they mean:
Picture origins:
Creepy picture of James Holmes
Edit of Jeff Weise
Drawing by Dylan Klebold
Screenshot from a video by William Atchinson showing off his gun
Dylan Klebold's computer, whiche he destroyed
Round found at Sandy Hook
An image claimed to be Adam Lanza but is actually an Australian man attempting to commit a sexual assault
Self explanatory, false flag conspiracies
Alleged picture of Seung Hui Cho, almost certainly is not
See here.
Explanations:
Columbine basement tapes / Nixon tape - You better know this
Crisis actors - Part of a larger hoax theory that victims in shootings are actors and the shootings didn't happen
FOIA - Freedom Of Information Act, which lets people request unreleased information and is how a good portion of mass shooting evidence is usually obtained
r/Columbine, r/masskillers - Controversial subreddits with self-explanatory names
The Columbine effect - See here (TLDR; Columbine has inspired or influenced dozens of attacks since)
Gun control - The idea that school shootings / mass shootings can be stopped via gun control laws
Carter Boyles - Also known as Bob8466, a 15-year old who planned a shooting but instead committed suicide. See here and here
Gmod shooting recreations - After almost every shooting, someone recreates in in gmod or other games. See here.
V-Tech Rampage - A video game based off of the Virginia Tech shooting
The Slaying of Sandy Hook Elementary - A video game based off of the Sandy Hook shooting
School Shooter: North American Tour 2012 - An (unreleased, I think) video game recreation of a school shooting
False flag attacks - Conspiracy theory that school shootings are staged for social and political manipulation
2006 Volleyball shooting
Boston Marathon bombing man on roofSol Pais - A teenaged girl obsessed with the Columbine who drove across states to the school to shoot herself with a shotgun in the woods behind it. Unknown whether or not she planned an attack or a suicide.
AR-15 connection - The weapon of choice of many mass killers
Victims of mass shootings not dead - Hoax theory
"Do you believe in God?" - A quote used by Klebold, Jeff Weise, and Chris Harper Mercer
Columbine minecraft map - Self-explanatory
Gmod Christchurch shooting map - Due to the livestream, recreating the scene in video games was easier than normal, and was of course done.
Super Columbine Massacre RPG - A video game based on Columbine that spawned the forum that proceeded this one. Played (or known to) several school shooters.
Adam Lanza created via face morphing- The claim that not only did Sandy Hook not happen, Adam didn't exist as a person in the first place
Shooter on the roof
E&D raped by police
Mass shooting cults
Columbine hand signals
Columbine bunker
Walmart
FaithMental illness - Self explanatory, the theory that mental illness is the reason why most school shootings happen
SSRIs to blame - Self-explanatory, the theory that SSRIs are the reason why most school shootings happen
Columbine predicted 9/11 - The boys fantasized about escaping the crime scene, killing more people, hijacking a plane, and crashing it into a builing in New York. Two years later, 9/11 happened.
Pictures of Adam leaked on 4chan - See this thread
"Popping noises" - A term often used by witnesses to describe gunshots
FOIA refusals - A lot of the time, sensitive evidence like CCTV footage or crime scene photos are not released in FOIA requests.
Doom connection - A large number of school shooters liked Doom over the years.
Mass shooting cover ups - The opposite of the hoax theory, that more mass shootings than are commonly reported actually happen but the situation is covered up.
WTC7 - Another building that collapsed on 9/11 and ties into lots of conspiracy theories. Unsure why it's on this list besides having to do with a terrorist attack.
Columbine 9/11 call
Shooter in the theatre
Returned a weekBowling Green massacre - A terrorist attack mentioned by Kellyanne Conway in 2017 that never actually happened.
Transgender mass shooters - Randy Stair, one of the Stem shooters, and refers to a theory that more of them are
Forgotten mass shootings - If a shooting isn't good for political talking points (ex. 2020 Thailand shootings,) no matter the death toll, it's swept under the rug and barely reported.
Eric shot Dylan - A debunked Columbine theory. In reality, Eric's brain matter was found beneath the burnt layer on the table, indicating Dylan was alive to set a bomb after Eric's suicide.
Dylan shot Eric - This one's new to me, but presumably similar to the Eric shot Dylan theory.
Guns jamming at random - Seems to occur in mass shootings a disproportionate amount of the time, sometimes even completely preventing attacks
Drum magazines - A kind of magazine widely used in mass shootings because of it's high number of rounds.
Ryan Lanza real shooter at Sandy Hook - Joke theory that Adam was framed, grew out of the confusion due to Adam's two coats on the parking lot and him having Ryan's ID.
Columbine bombs would have killed nobody - Even if the timers were set right, the bombs were made incorrectly and wouldn't have done much more than start a small fire.
Nancy Lanza worked at Sandy Hook - A claim widely made by news after the shooting that was not true.
Seung Hui Cho manifesto - He mailed it to NBC, and only fragments have ever been released.
Homemade guns used in mass shootings - Halle is the most famous, but many other shootings used homemade weapons. Probably included as evidence that gun control wouldn't effectively combat the problem
Charles Whitman copycats - Not 100% certain that this is what it means, but probably refers to Charles Whitman having a far greater impact on future school shootings than he is normally credited with. Anthony Barbaro might have been influenced by him, who then influenced Michael Slobodian and Robert Poulin, and it snowballed from there.
Unborn children
Mass shootings in EuropeWolfgang Halbig - A Sandy Hook conspiracy theorist who harassed survivors and was arrested.
Vance Stone - William Atchinson's youtube username.
Randy Stair lost media - The mediafire package was thought to be lost at point point, could be referring to the CCTV or rumors that he livestreamed it
"We Need To Talk About Sandy Hook" - Documentary about Sandy Hook hoax theory.
KMFDM - Band liked by many school shooters, basically the Natural Born Killers of music.
Blackjack Pizza - Where E&D worked. Could be referring to the idea that the pizza place or something related to it played a role in the massacre.
Columbine crime scene photos on deep web - Creepypasta-tier rumor, false
E&D homosexual relationship - Largely disproven but a theory that lives on in movies such as Elephant. Popularized by the confusion resulting from Dylan writing about wanting to do a massacre with a girl he liked and people thinking the "love" he was referring to was Eric, which it was not.
Stephen Paddock powerpuff girls - An image of Paddock and his brother inexplicably has a reflection of the Powerpuff girls in the background. It also refers to his email address,
[You must be registered and logged in to see this link.].
Brenton Tarrant magazine already on ground - The conspiracy theory that the Christchurch stream and shooting was faked, as some people claim a written-on magazine of his was already on the ground when he entered the mosque.
Lcaress - AOL account claimed to belong to Eric Harris that did not.
Elliot Rodger reddit account
Withheld from public
Nikolas Cruz 4chan post
Australia
Steam account
Mass shooting Steam groups
FEMA"What's wrong with being a devil?" - Unsure, probably a quote from the movie Village of Doom based on the Tsuyama massacre
Nevada-tan - An 11-year old girl in Japan who killed a classmate with a boxcutter. Became an internet celebrity in the 2000s and her identity was leaked.
Sandy Hook victims at Super Bowl - The idea that the shooting was faked and that alleged "victims" were seen in videos from the Super Bowl.
FBI refuses to research possible mass shooters - The theory that mass shootings aren't faked, but are intentionally not prevented. Popularized by Nikolas Cruz's obvious planning which the FBI ignored.
Cannibalwolf - Member of online mass shooting communities. I don't know for sure, but I think something bad happened to him.
Lance Stone - William Atchinson's youtube username.
Basement tapes on the deep web - Creepypasta tier rumor / shitpost
/X/ Columbine threads - Every so often Columbine threads crop up on the /x/ 4chan board and develop far-fetched but interesting theories about the shooting (I recall one that it was all a ritual to immortalize themselved, which seems to have succeeded.)
Mass killings in ancient Greece - The earliest known mass killing (as least as we know them) was in Ancient Greece when a wrestler tore down a column at a school house and crushed many inside to death in the collapse.
Adam Lanza = Randy Stair - Shitpost theory inspired by some of their physical similarities (which I don't really see, but whatever.)
Natural selection - Eric Harris's justification and a repeated theme in school shootings since
Woo Bum-Kon - One of the deadliest mass killers, but barely anyone even knows who he is. See "forgotten mass shootings."
Mass Shooter youtube accounts
"Why is this happening? I just want to go home."
Playing ColumbineLost Amazing Athiest Auvinen video - A video of Amazing Atheist talking about Auvinen more his shooting.
"Where to buy cheap assault rifle" - The William Atchison post that got the cops called on him.
Port Arthur massacre false flag - Self-explanatory, largely involves the idea that such a challenged individual would not be able to kill that many people that quickly.
Morimiya Middle School shooting - An anime style video game about a mass shooting
Ax Ishmael - What Seung Hui Cho had written on his arm and signed his multimedia manifesto as when he mailed it.
Eric Harris in window
Columbine suicide photos altered
Matrix and Columbine
Mass shooters named "Dylan"
Search history
Stoneman Douglas will never be released
1973 Delaware school shooting
Robert Holmes and Peter Lanza
"Victim clothing"Gabby Gilfords died - The senator targeted in the Tuscon shooting who was shot in the head but miraculously survived. Loughner did not believe she did and thought she was replaced, this is the theory that she actually was.
"I don't like Mondays" - What Brenda Spencer told a reporter over the phone when asked for her motive
James Holmes IEDs - Holmes left explosives at his apartment, but told the police about them for some reason. A neighbor nearly set them off.
Adam Lanza pedophile - The perspective that his interest in childrens rights was due to pedophilic interests
Natural Born Killers - A movie that many school shooters liked
Adam Lanza bed made - In the photos of his room, his bed is made. Pointed out by some as evidence for a hoax, pointed out by others as a strange aspect of the case and himself.
Sam Hyde - He is behind every shooting and can't keep on getting away with it.
Most of them were killed by SWAT - The largely non-serious Columbine theory that the police response was so bad it killed more people than the shooters and there was a cover up of it.
Lax Shooting mannequin
Robbie Parker
John Doe
Whiskey_Warrior_556
Real death count of COlumbine
James Holmes youtube channel
Boston Marathon bombing purse
Far more people
Seung Hui Cho didn't act alone
Japanese mass shootingYou know a mass shooter / future mass shooter - Given recent events, it doesn't seem to unlikely.
GTA San Andreas Columbine mod - Self explanatory
Jokela School Shooting flash game - Jokela High Massacre, seemingly deleted.
Dawson Flash Game - Dawson College Massacre!
Nobody died at Sandy Hook - Theory that the shooting was a hoax
Sanpaku eyes - Claims that some mass shooters (ex. Lanza) have unusually wide Sanpaku eyes
"I am the joker" - What James Holmes allegedly said when arrested, turned out to be false
E&D got the guns from police - A variant on the Columbing hoax theory, that the shooting was real but it was assisted by outside agencies
MK Ultra causes mass shootings - Psychological manipulation by the government is used to push vulnerable individuals over the edge to justify infringing on rights.
Bethel High School shooting
Columbine is haunted
Fort Hood is cursed
Student with his face hanging off
Zero hour Virginia Tech
Potato skins
Larry PoznerEvery mass shooting is a hoax - Self explanatory.
Hobbies: Semper fidelis - A quote from Eric's AOL profile.
eldigato - One of William Atchinson's username.
When in doubt, pull it out, "Shut up and shoot it'' and "Quit whining, it's just a flesh wound ... Kill Em AALLLL!!!!'' - Quotes from Eric Harris's AOL profile.
Gun free zones
Songs about mass shootings
Motive unknown
Kiwifarms
Omar Matteen private security
Dedrick Owens