An increasingly popular name for the post-apocalyptic world in which the events of the My Chemical Romance 2010 album "Danger Days: The True Lives Of The Fabulous Killjoys" take place. The year is 2019 or thereabouts, and an unknown, but likely nuclear disaster, has turned the world into a place similar to the setting of the Fallout series.
Term never officially used by the band, but coined by a fan in a popular tumblr blog very early in the album's history.
There's been Dangerverse fanfiction ever since the first Danger Days single was released, but it's really ballooned after the full album release.
The Alternate Universe worlds in which Harry Potter is raised by Remus Lupin, Danger Granger Lupin, Aletha Freeman Black, and Sirius. His siblings and pack-mates are as follows: Draco Reggie Black, Hermione 'Neenie' Granger Lupin, Meghan Lily Black, Luna Lovegood, Ron and Ginny Weasley, and Neville Longbottom. It is characterized by a mostly wonderful, occasionally evil style in which there are happy endings, cute songfics, intellectual intrigue, and epic battles. Oh, and DB/LL as well as MB/NL.
The Dangerverse has a story where one version of Harry Potter sings Christmas songs while another fights Voldemort. Don't you just love crossover fics?