The Joker is a major antagonist of the DC Extended Universe, appearing as an unseen antagonist of Batman vs Superman: Dawn of Justice, a major antagonist of Suicide Squad, the overarching antagonist of Birds of Prey (And The Fantabulous Emancipation of One Harley Quinn), a minor anti-hero of Zack Snyder's Justice League and an unseen antagonist of The Suicide Squad.
He is Batman's archenemy, the lover of Harley Quinn, and a psychopathic crime lord and terrorist mastermind.
He is portrayed by Jared Leto.
Flashbacks in the film reveal that Joker manipulated psychiatrist Dr. Harleen Quinzel into falling in love with him during his time as a patient at Arkham Asylum. He eventually manages to convince her to free him, and after his men take over the asylum, he gives Dr. Quinzel electroshock therapy. Quinzel then volunteers to jump into the chemicals that created the Joker, bleaching her skin and completing her transformation into his lover, Harley Quinn. The Joker and Harley would then be known as the "King and Queen of Gotham". However, Quinn is ultimately apprehended by Batman, and is forced to join Amanda Waller's government task force comprised of captured supervillains.
In present day, the Joker attempts to extract Harley from the "Suicide Squad". He tortures one of Waller's security officers into leading him to the facility where the nano bombs used to control the criminals are manufactured, and threatens one of the scientists there to disable the bomb implanted in Harley's neck. Joker then gives the security officer a cell phone to give to Harley, so that he can signal her when to escape. After commandeering one of Waller's helicopters, Joker and his men rescue Harley in Midway City. However, the chopper is shot down. While Harley jumps out onto a nearby building, Joker seemingly perishes in the explosion, prompting a heartbroken Harley to rejoin the Squad. At the end of the film, the Joker, revealed to have survived the crash, breaks into Belle Reve prison to free Harley from her cell, and the two reunite before Joker says, "Let's go home."