Dylan Klebold and Eric Harris
Dylan Klebold and Eric Harris were two students who committed the Columbine High School massacre. They tragically killed 13 students together. What drove them to do the shooting was their rejection and bullying by their classmates. Eric Harris was involuntarily not getting laid
Incel Wiki does not support or condone the columbine high school murderers or their crimes.
Sexual Frustration and incelibacy
Dylan and Eric were probably bullied due to sexual reasons. Eric Harris e.g. experienced a great deal of rejection by women, once writing up women who rejected him in a list of people who he thought, "should have died". Eric most likely died a virgin according to careful analysis of his life.
The quote above suggests Eric felt the attack would have been avoidable if he could just, "get laid".
In his last journal entry, Eric Harris lamented the fact that he couldn't "fuck", suggesting having sex was a top priority for him, and complained about not getting any despite being nice and considerate.
Researchers, led by Daniel Provenzano from the University of Windsor in Canada, found that bullying probably evolved as a behavior for men to show their strength and assert dominance, while signaling to women that they are good prospective mates who will provide for their needs and offspring. Professionals dealing with young adults need to recognize the role of sexual motivation in bullying, suggests Provenzano. 
Eric Harris made Doom levels.