Earth-90

Earth-90   is one of the many universes in the multiverse.

History
In late 2018, Mar Novu/The Monitor ravaged the Earth of this universe and then used the Book of Destiny to massacre all its inhabitants, leaving Barry Allen as the only survivor.

From The Monitor's realm

 * Mar Novu

Behind the scenes

 * The number 90 is a reference to the original '90s Flash television series.
 * Marc Guggenheim later confirmed on Twitter that the '90s series actually takes place on Earth-90.
 * The dead warriors of this Earth, while not named, depict various versions of DC Comics characters. These include Stargirl, Hawkgirl, Huntress, Hawkman, Green Arrow, Captain Cold and Firestorm.