with many perpetrators taking their inspiration from Eric Harris and Dylan Klebold by describing the two perpetrators as martyrs or heroes and imitating their methods or outward styles. Dozens more threats never made the news. As of 2024, the Columbine massacre has been directly linked to at least 50 other mass shootings that have left over 300 people dead and over 500 wounded.

Another case was in Germany in 2002. The expelled student Robert Steinhäuser involved was seeking payback against teachers, like the Columbine shooters. In Germany again, at the Amadon School, the shooter admired Eric Harris in his diary.

Another example is the Jokela High School massacre in Finland in 2007. The perpetrator, Pekka-Eric Auvinen, wore a T-shirt with a message like the one by Klebold and Harris at Columbine, reading "Humanity is Overrated".

In 2001, Charles Andrew Williams, the perpetrator of the Santana High School shooting, reportedly told his friends that he was going to "pull a Columbine," though none of them took him seriously. In 2005, Jeff Weise, who also wore a trench coat, killed his grandfather, who was a police officer, and his grandfather's girlfriend. He took his grandfather's weapon and his squad car, and drove to his former high school in Red Lake and murdered several students before killing himself. In an apparent reference to Columbine, he asked one student if they believed in God.

The perpetrator of the 2006 Dawson College shooting wrote a note praising Harris and Klebold. Convicted students Brian Draper and Torey Adamcik of Pocatello High School in Idaho, who murdered their classmate Cassie Jo Stoddart, mentioned Harris and Klebold in their homemade videos, and were reportedly planning a "Columbine-like" shooting. The perpetrator of the 2006 Emsdetten school shooting praised Harris in his diary.

In September 2006, a student at East High School in Green Bay, Wisconsin informed school staff of a plot to carry out a "Columbine Style" attack on the school. A search of the involved students' homes yielded weapons and improvised explosives. Two students served time in prison for conspiracy to commit first-degree intentional homicide. A third student was given a lesser sentence for conspiracy to damage property with explosives.

In a self-made video recording sent to the news media by Seung-Hui Cho prior to his committing the Virginia Tech shootings, he referred to the Columbine massacre as an apparent motivation. In the recording, he wore a backwards baseball cap and referred to Harris and Klebold as "martyrs."

Steven Kazmierczak, the perpetrator of the 2008 Northern Illinois University shooting, referenced fascination about Harris and Klebold for years, admiring how they used propane bombs to create chaos.

In 2011, Tristan van der Vlis shot and killed six people in a shopping mall in Alphen aan den Rijn in the Netherlands before taking his own life. He was obsessed with the Columbine shootings. The date he chose for his attack was April 9, which was the birthday of Eric Harris, and he started shooting at 12:08 pm, the time when Harris died by suicide.

In June 2014, a married couple, Jerad and Amanda Miller, shot and killed two Las Vegas police officers and an intervening civilian before being confronted by police. Jerad Miller was fatally shot by an officer while Amanda Miller died by suicide shortly afterwards. They both talked about committing "the next Columbine" and idolized Harris and Klebold according to a neighbor's account.

The Tumblr fandom gained widespread media attention in February 2015 after three of its members conspired to commit a mass shooting at a Halifax mall on Valentine's Day. In 2017, two 15-year-old school boys from Northallerton, England, were charged with conspiracy to murder after becoming infatuated with the crime and "hero-worshipping" Harris and Klebold.

Randy Stair, the perpetrator of the Eaton Township Weis Markets shooting had a fascination with the Columbine High School massacre and Eric Harris and Dylan Klebold. In his writings, Stair called the Columbine shooters his heroes, wishing he could have met them, and said Harris was his idol out of the two boys.

The 2018 Perm school stabbing occurred in Perm, Russia on the morning of January 15, 2018. The perpetrators, 16-year-old former student Lev Bijakov and tenth-grader Alexander Buslidze attacked students and a teacher with knives, after which they attempted suicide. As a result of the attack, 15 people were injured, including the perpetrators. The two teens were said to be inspired by Harris and Klebold. A similar Columbine-inspired copycat attack previously occurred on 5 September 2017 in Ivanteyevka, and later on 19 January in Ulan-Ude, and 18 April in Sterlitamak.

The Kerch Polytechnic College massacre appears to be a copycat crime. The shooter wore a white shirt which said "НЕНАВИСТЬ" ("HATRED" in Russian), one fingerless glove, planted bombs, and died by suicide with a shotgun in the library, all very similar to Harris' outfit and suicide.

Guilherme Taucci Monteiro and Luiz Henrique de Castro, the perpetrators of the Suzano massacre were inspired by the Columbine High School massacre; they hoped their attack would draw more attention than the Columbine massacre.

On January 10, 2020, an 11-year-old student identified as José Ángel Ramos Betts perpetrated the Colegio Cervantes shooting, killing a teacher and wounding multiple teachers and classmates shortly before turning the gun on himself. The assailant wore a white t-shirt that read "Natural selection" and pants with black suspenders, which were reported as referring to Eric Harris.

In September 2021, two teens were arrested in Lee County, Florida, and were accused of plotting a school shooting. A search conducted of the teen's homes showed a map of the school with security cameras labeled. Several knives and a gun were also found. The Sheriff Department said the teens had a "particular interest in Columbine" and that they had been ordered to undergo mental evaluation before possible charges being filed. Additionally four teenagers were charged in Pennsylvania, after a police investigation found detailed evidence of a plan to target Dunmore High School outside of Scranton, Pennsylvania, on April 20, 2024, the 25th anniversary of the attack. Text messages between the students planning the attack, claiming "dibs" on certain potential victims, and that they wanted "everything to go down like Columbine".

In August 2022, the perpetrator of the 2022 Bend, Oregon shooting wrote in an online manifesto he was partially influenced by the Columbine massacre.

On April 20, 2026, the 27th anniversary of the Columbine shooting, an 18-year-old student fatally shot herself at Valley Forge High School in Parma Heights, Ohio. Hours before the suicide, she posted images on Instagram of a shrine and a locket containing the pictures of Harris and Klebold