Joker (Earth-1: Post-Crisis)

"Gotham City and me, we just... Have a bad history with freaks dressed like clowns."

- Bruce Wayne

An unnamed man known only as Joker is an infamous crime boss stationed in Gotham City and a known enemy of the vigilante known as Batman.

He is the ex-boyfriend of Harley Quinn.

Early life
At some point, the man felt into a vat of chemical at ACE Chemicals causing him to become a psychotic criminal today known as "Joker".

At some point, the Joker ended up being a frequent enemy of "The Batman" to the point where he was locked in Arkham Asylum. At one point after being locked up, he managed to make Dr. Harleen Quinzel fall in love with him and with her help, he caused a riot and a breakout of the asylum after shocking her. At some point, Joker was pursued with a broken-hearted Harleen Quinzel who almost kill him until he manipulated her feelings to get out of this situation. Later, the joker would bring her to ACE Chemicals to make her fall into the same vat that changed him before jumping in. This would cause Harleen to become his accomplice known as "Harley Quinn". At some point he and Harley killed Batman's protégé Robin. At some point in 2014 Joker murdered the crime boss Monster T inside his strip club due to him considering Harley "his girl". That night, Joker and Harley were driving a car and were pursued by the Batman. The car would eventually end up in a river where Joker escaped leaving Harley to be arrested.

Finding Harley
In 2016, Joker henchman Jonny Frost informed him that Harley was imprisoned in Belle Reve. At the news, the Joker ordered Frost to prepare the car and lied down laughing. Joker would bring Hunter Griggs the captain of Belle Reve in order to torture him and get information on the Suicide Squad. After getting information out of him, he gave him one last task to deliver a phone to Harley where he could communicate with her. Joker would then break into the A.R.G.U.S. facility that fabricated the bombs planned in Harley's head and plant a bomb inside Dr. Van Criss in order to make him cooperate in disarming the bomb. Later, Joker would steal an army chopper and use it as an opportunity to save Harley. Once Harley was attached to the rope, they depart but their helicopter was shut down by A.R.G.U.S. causing a crash leaving Harley to believe that he died.

At some point after Harley was re-imprisoned in Belle Reve, the Joker and his gang broke inside the prison and released Harley.

Life with Harley
At some point, he and Harley would cause fear in the heart of Gotham City's mobs to the point where Harley gave Joker challenges that made Harley a lot of enemies.

Breakup
At some point between August 9, 2016 and 2020, Joker broke up with Harley. This caused her to destroy ACE chemicals in order to make it official.

Trivia

 * Despite Jared Leto not being able to appear due to schedule in, Johnny Goth took his place to film the necessary scenes.
 * Joker appears in Suicide Squad for about 7 minutes and 20 seconds.