Eric Harris and Dylan Klebold

Eric David Harris (April 9, 1981 – April 20, 1999) and Dylan Bennet Klebold (September 11, 1981 – April 20, 1999) were American high school seniors who perpetrated the Columbine High School massacre at Columbine High School on April 20, 1999 in Columbine, Colorado.

Harris and Klebold killed 12 students, one teacher, and wounded 24 others.

After killing most of their victims in the school's library, they died by self-inflicted gunshot wounds.

At the time, it was the deadliest high school shooting in U.S. history.

The ensuing media frenzy and moral panic led to "Columbine" becoming a byword for school shootings, and becoming one of the most infamous mass shootings ever perpetrated in the United States.

Harris and Klebold were both born in 1981.

Harris was born in Wichita, Kansas, but moved around frequently as a child due to his father's occupation in the United States Air Force, while Klebold was born and raised near Columbine.

Eric David Harris was born on April 9, 1981, in Wichita, Kansas.

Harris's parents were both born and raised in Colorado.

His mother, Katherine Ann Poole, was a homemaker.

His father, Wayne Harris, was working in the United States Air Force as a transport pilot.

In 1983, the family moved to Dayton, Ohio, when Harris was two years old.

Six years later, the family relocated to Oscoda, Michigan.

Michigan pastor William Stone lived across the street from the Harris family while they were located in Oscoda.

Stone recalled them as "great neighbors" and often saw Wayne very engaged with his sons.

The Harris family then moved to Plattsburgh, New York, in 1991.

During his time at Stafford Middle School, Harris played Little League Baseball, regularly went to birthday parties and was "part of the crowd".

Kyle Ross, a former classmate of Harris, said, "He was just a typical kid."

The Harris family finally settled back in Littleton, Colorado the next year when Wayne retired from the military.

Harris's family eventually settled in Colorado in 1992.

Shortly after, Harris and Klebold met while they were in the 7th grade.

Over time, they became increasingly close.

By the time they were juniors in high school, they were described as inseparable.

There are differing reports; some say Harris and Klebold were very unpopular students once they were upperclassmen, as well as frequent targets of bullying, while others say they were not near the bottom of the school's social hierarchy and that each had many friends, along with active social lives.

Columbine High School was known to have an intense "jock culture", which saw popular students, mainly athletes, benefit from special treatment from faculty and other students.

According to their journal entries, Harris and Klebold had seemed to begin planning the attack by May 1998, nearly a year before the attack.

Throughout the next eleven months, Harris and Klebold meticulously built explosives and gathered an arsenal of weapons.

Both Harris and Klebold each left behind several journal writings and home videos, ones they made both alone and together, foreshadowing the massacre and explaining their motives.

Harris and Klebold hoped this content would be viewed by the public extensively and inspire followers, although much of the evidence has never been released by authorities.

Harris and Klebold often wore trench coats in school, and in general, as part of their everyday outfits, so after the massacre, it was widely believed Harris and Klebold were part of a clique in school called the "Trenchcoat Mafia", a group of misfits in the school who supposedly rebelled against the popular students.

This turned out to be untrue, as neither Harris nor Klebold had any affiliation with the group.

The pair's aforementioned writings and videos gave insight into their rationale for the shooting.

The FBI concluded that Harris was a psychopath, who exhibited narcissistic traits, unconstrained aggression, and a lack of empathy, while Klebold was concluded to be an angry depressive with a vengeful attitude toward individuals who he believed had mistreated him.

However, neither Harris nor Klebold were formally diagnosed with any personality disorders prior to the attack, so this conclusion is often debated.

In the following years, various media outlets attributed multiple motivating factors to the attack, including bullying, mental illness, racism, psychiatric medication, and violence in music, movies, and video games.

Despite these conclusions, the exact motive for the attack remains inconclusive.

Harris and Klebold have become pop culture icons, with the pair often portrayed, referenced and seen in film, television, video games, music and books.

Many killers since the shooting have taken inspiration from the pair (dubbed the Columbine effect), either hailing them as heroes, martyrs and gods, or expressing sympathy for them.

Harris and Klebold also have a fanbase, who have coined the term "Columbiners", who write fan fiction and draw fan art of them.

Others have also dressed as the duo for cosplay or Halloween.