Danger Days: The True Lives of the Fabulous Killjoys (often referred to as simply Danger Days) is the fourth studio album by the American rock band My Chemical Romance, released on November 22, 2010 by Reprise Records. Its songs are associated with the band's well known sound of alternative rock, pop-punk, and punk rock, along with an introduction of new musical elements, including power pop, pop rock, and electronic rock. The primary musical inspiration for the album came from contemporary rock, psychedelic rock, and protopunk bands of the sixties and seventies. It was the penultimate album released by the band before their six-year disbandment from 2013 to 2019.

Like the band's previous album The Black Parade, Danger Days is a rock opera. The album's storyline takes place in post-apocalyptic California in 2019, where a group of rebellious outsiders known as Killjoys battle against an evil corporation. In 2013, frontman Gerard Way published a comic that continues the story described in the album.

To promote the album, the band embarked on a world tour, titled The World Contamination Tour. It lasted from October 2010 to February 2012, and included concerts in Europe, North America, Asia and Oceania; the band also co-headlined the 10th Annual Honda Civic Tour with Blink-182. Danger Days received generally positive reviews from critics and sold 112,000 copies in its first week, debuting at the top of the Billboard Rock Albums and Alternative Albums charts, and at number 8 on the Billboard 200. It also appeared in the music charts in several other countries. By February 2011, Danger Days had sold over a million copies worldwide.