"Thoughtless" is a song written by American nu metal band Korn for their fifth studio album, Untouchables. "Thoughtless" was released as the album's second single sometime in July 2002.

"Thoughtless" is about the Columbine High School shooting through the eyes of the murderers. Jonathan Davis, the vocalist of Korn, said that "Thoughtless" is "a song about people who are constantly ridiculed and the collateral damage it can cause".

This song was introduced to fans during a live show at the Hammerstein Ballroom, in NYC on June 10, 2002, which celebrated the release of the band's fifth album, Untouchables. This performance appears on the DVD release entitled Live. "Thoughtless" has been played during the Untouchables promotional tour, in 2002, but it was scrapped from the band's set list one year later. It eventually returned in 2006 on the See You on the Other Side World Tour as a part of a . The full song was played at the 2006 Family Values Tour and the Escape from the Studio Tour. It has most recently been performed within a medley at the Music as a Weapon V tour. The song was well received.

In the beginning, a high-school aged boy (who is revealed to be called Floyd Louis Cifer in a yearbook) (portrayed by Aaron Paul) is walking through the hallways of his school. Four girls are teasing and looking at him in disgust. A group of jocks on the other side of the hallway give him dirty looks and then beat him up. In the next scene, the boy is in his science class drawing strange pictures of his pain in his notebook. Song titles from Untouchables can also be seen. He goes to the pool to swim and the jocks see him there and bother him. After that, he is in the locker room wrapped in a towel and is seen sweaty and increasingly agitated. We then see him in his room looking at his yearbook. He throws the year book at his window and looks in the phone book for a service that says "Fantasy Escorts." He calls the service then shows up at his prom with a woman (portrayed by Aimee Sweet). He vomits on everyone who had bullied him and gets his revenge. Korn performs inside his brain throughout the video. Aaron Paul's character's name appears in his yearbook as "Floyd", which was the working title for "Thoughtless" on the unmastered, leaked version of Untouchables.

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