Joker (Gotham)
Real name: Jeremiah Valeska
Aliases: Xander Wilde, Mr. J
Creator: DC Comics
First appearance: A Dark Knight: Mandatory Brunch Meeting"
Occupation: Cult leader (formerly) Criminal mastermind Terrorist Structural Engineer (formerly)
Relatives: Lila Valeska (mother)
Paul Cicero (father)
Jerome Valeska (twin brother)
Zachary Trumble (uncle)
Height: -
Weight: -
Superpowers: Agility, Durability, Enhanced Memory, Intelligence, Marksmanship, Stealth, Weapons Master
Stats: intelligence 100, strength 10, speed 15, durability 60, power 50, combat 70

History:
Jeremiah Valeska is a terrorist, criminal and murderer. He is also the more arrogant and obsessive identical twin brother of the anarchistic cult leader, Jerome Valeska. After Jerome's death and being exposed to his altered chemical laughing toxin driving him to insanity, Jeremiah takes over the role of main antagonist for the final arc of Season Four and a major antagonist in Season Five.  As a child, Jeremiah supposedly suffered years of abuse at the hands of his insane brother, who apparently burnt Jeremiah's bed while Jeremiah himself was in it. Jeremiah would in turn manufacture several lies about his brother that would turn Jerome's entire family against him; it remains unclear how much truth there was in either story. In a desperate attempt to defend Jeremiah from his monstrous brother, his uncle took him away from Haly's Circus, in which his mother Lila worked, and proceeded to take him to St. Ignatius. Following this Jeremiah changed his name and started calling himself Xander Wilde. After finishing school, Jeremiah became a brilliant engineer, designing highly advanced generators for Wayne Enterprises. He also built a labyrinth hideout to protect himself from his brother, which took almost six years of construction. In addition to the hideout which he filled with security cameras, rooms of work and more, he met a young woman named Ecco who started to work for him as a proxy and assistant. Jeremiah would later reunite with his brother, who after a rampage to find his twin, found him in his hideout. Right after witnessing his brother's death, Jeremiah received a gift sent by Jerome, which is revealed to be a "special" gas created just for him. Upon inhaling it, his face became pale white and a wide red grin formed from ear to ear, finally giving Jeremiah the drive to explore that dark side of him that his brother Jerome had seen. Becoming obsessed with both Bruce Wayne (whom he quickly became friends with each other) and re-building Gotham in his own image after destroying it, he eventually formed an alliance with Ra's al Ghul. After mortally injuring Selina Kyle in an attempt to destroy Bruce's attachments and drive him insane, Jeremiah killed the mayor and demolished all of Gotham's bridges, cutting the city off from the rest of the world and paving the way for Bruce to become the "Dark Knight" Ra's had foreseen. With Gotham City reduced to a lawless "no-man's land", Jeremiah managed to escape into the night, remaining on the loose in the abandoned city. After Selina recovers, she tracks down Jeremiah and stabs him multiple times with the intent to kill him. Jeremiah survives and proceeds with his plan to reenact the Wayne murders, using Jim Gordon and Lee Thompkins as stand ins, hoping their murders would give him and Bruce a permanent connection. His plan is foiled by Selina’s intervention, and Jeremiah is severely disfigured and brain dead after falling into a vat of chemcials - which ultimately leads to him losing his identity. He is currently in a coma whilst in the custody of Bruce Wayne. Despite this, his secondary plan to prevent the reunification with the mainland succeeds, leaving Gotham’s river polluted with toxic chemicals.

Powers:
Jeremiah is shown to be highly intelligent. Since he was a child, he used to draw mazes, and when he grew up, after having the best grades at school, he built one in his house, which he built underneath the woods. Furthermore, he is extremely manipulative as he was able to keep anyone from discovering his insanity for years, even after it was brought to the forefront by Jerome's gas, and he was able to convince everyone that he was Jerome in the tapes he sent to Jerome's followers and the GCPD. Jeremiah also claims to be "vastly more intelligent" than Jerome was. He is a brilliant engineer, designing advanced generators capable of powering Gotham that could double as powerful explosive devices.