Jack Oswald White is the Joker's real identity, according to DC's Flashpoint Beyond
Writers Geoff Johns, Tim Sheridan, and Jeremy Adams, artists Xermánico and Mikel Jann, colorists Romulo Fajardo Jr. and Jordie Bellaire, and colorist Rob Leigh are the creators of Flashpoint Beyond
Batman/Thomas Wayne learned that his wife, Martha Wayne, who had previously transformed herself into the Flashpoint Universe's Joker
was the enigmatic Clockwork Killer in Flashpoint Beyond
In Flashpoint Beyond #5, Thomas enters Arkham Asylum to confront Martha
which leads to a fight that is interrupted by a few security personnel.