Warning! Spoilers for Flashpoint Beyond #5 by DC Comics
DC Comics has given the Joker a new real name, as the Clown Prince of Crime is referred to as "Jack Oswald White" in a new time-hopping story. In Flashpoint Beyond #5 by DC Comics, the Flashpoint version of Martha Wayne, who became the Joker in her universe, revealed that she was told about the Joker in the main DC Universe where Bruce survived. She shares a story about the Comedian from her world and refers to him by his real name.
Part of what makes the Joker such a mysterious and twisted villain is that his real name was unknown in most continuities. The Batman villain has been given a few potential real names, with his most common first name being Jack. That name seems to be inspired by the Joker's real identity in Tim Burton's Batman, where Jack Nicholson's Joker was named Jack Napier. That name carried over into Batman: The White Knight, as the alt-universe story also featured a former Joker named Jack Napier. Joker has also been referred to as "Sonny," and in the Joker movie starring Joaquin Phoenix, his real-life name was Arthur Fleck. Now, DC Comics is giving Joker a new real name: Jack Oswald White.
In Flashpoint Beyond #5 by Geoff Johns, Tim Sheridan, Jeremy Adams, Mikel Janin Xermanico, Romulo Fajardo Jr., Jordie Bellaire, and Rob Leigh, Flashpoint Batman arrives at Arkham Asylum to deal with the shocking return of the Clockwork killer, who is his former wife and current Joker, Martha Wayne. After locking himself in a cell with Martha as police try to stop her, the Joker reveals that when Psycho-Pirate arrived in their universe, she made him tell him everything about the world her son Bruce was alive in. Learning Joker was a man in his world, she reveals she visited him in the Flashpoint timeline.
It turns out the man who didn't become the Joker while Martha Wayne did instead was named Jack Oswald White - a failed comedian stuck in a dead-end job cleaning bathrooms at Wayne Casino. However, despite his hard life, he found solace because he was part of a happy family. So while it's the Flashpoint version of the man who became the Joker in the main DC Universe, his real name might hint at what the actual Clown Prince of Crime was called before his dark turn. Especially considering most, if not all, Flashpoint versions of characters share the same name as the main DC Universe counterparts.
The reveal about the Joker from the Flashpoint Universe being named Jack, as it has been hinted at before in other universes, helps add credence to the possible real first name of the DC villain in the main reality. However, is the main universe's Joker named Jack Oswald White? That's up for debate, but it's definitely a new contender for the Joker's real name.