Jack the Ripper is a fictionalized version of a real-life serial killer. The character was created by Brian Augustyn and Mike Mignola and first appeared in Gotham by Gaslight #1 (February 1989).

Jacob Packer had been trained in both medicine and law by Thomas Wayne while Martha Wayne rejected him. Packer hired an assassin to kill the two and afterwards personally killed women to "silence" his own insanity. Jack the Ripper frames Bruce Wayne for his killings in Gotham City. A trial was held in which Packer was a defense attorney yet Bruce was convicted, sentenced to be hanged and imprisoned in Arkham Asylum before eventually figuring out the killer's identity and escapes from prison with Alfred Pennyworth's help. Batman confronts Jack the Ripper throughout Gotham and the two eventually come to Thomas's and Martha's graves before he's killed by Inspector James Gordon.^[1]

Jacob Packer makes a non-speaking cameo appearance in Batman: Gotham by Gaslight,^[2] while Jack the Ripper's identity is instead utilized by James Gordon (voiced by Scott Patterson).^[2]

Aubrey James is a fictional character appearing in American comic books published by DC Comics.

Aubrey James is the mayor of Gotham City and a friend of Thomas Wayne prior to Thomas' murder. He is later murdered, as mentioned in The Madmen of Gotham.^[3]

Aubrey James appears in Gotham, portrayed by Richard Kind.^[4]

Java is a fictional character appearing in American comic books published by DC Comics. He was created by Bob Haney and Ramona Fradon, and first appeared in The Brave and the Bold #57 (January 1965).

Java is the Neanderthal servant of Simon Stagg, who discovered and revived him. Java is present when Rex Mason discovers the Orb of Ra in Egypt and transforms into Metamorpho. He pines for Simon's daughter Sapphire Stagg, but is rejected because she is in love with Metamorpho.^[5]

Simon Stagg later kills Java, but he resurfaces at Metamorpho's funeral.^[6][7] In Outsiders (vol. 4), Simon Stagg transforms Java into a Shaggy Man before Freight Train defeats him.^[8]

In the DC Rebirth relaunch, Java operates as the supervillain Doctor Dread and forms a counterpart of the Terrifics called the Dreadfuls.^[9][10]

• Java appears in the Justice League episode "Metamorphosis", voiced by Richard Moll.^[11]
• Java appears in The Flash episode "Fastest Man Alive", portrayed by Michasha Armstrong. This version is a contemporary African-American human and Stagg Enterprises' head of security who is killed by Multiplex.

The Javelin is a fictional DC Comics supervillain.^[12]

The Javelin is a former German Olympic athlete who turns to crime, using his athletic skills and a javelin-based weapons arsenal. He later joins the Suicide Squad in exchange for his criminal record being purged.

In Checkmate, Mirror Master recruits Javelin to frame Amanda Waller, during which he attempts to protect Jewelee and is killed after being run over by a runaway jeep.^[13]

• The Javelin makes non-speaking cameo appearances in Justice League Unlimited as a member of Gorilla Grodd's Secret Society.
• The Javelin makes a non-speaking cameo appearance in the Batman: The Brave and the Bold episode "Scorn of the Star Sapphire!".
• A character loosely inspired by the Javelin named Malcolm Byrd appears in the Arrow episode "The Demon", portrayed by Yanik Ethier. This version is a French arms dealer associated with the Ninth Circle.
• Gunter Braun / Javelin appears in The Suicide Squad, portrayed by Flula Borg.^[14] He is recruited into the eponymous group for a mission to Corto Maltese, but is fatally wounded by the local military and bequeaths his namesake to teammate Harley Quinn.

Jefferson Jackson is a supporting character of Ronnie Raymond (a.k.a. Firestorm) who makes his debut in Firestorm (vol. 2) #1 (June 1982). Jackson is a former student of Bradley High School in Manhattan, New York. During his time at Bradley High, Jackson joins the school's basketball team, where he meets and befriends Ronnie.

Jefferson "Jax" Jackson appears in media set in the Arrowverse, portrayed by Franz Drameh.^[15][16]

• Introduced in The Flash episode "The Fury of Firestorm", this version is a former high school football player who was injured when S.T.A.R. Labs' particle accelerator exploded and was forced to become a mechanic instead. Following Ronnie Raymond's death and due to Martin Stein's F.I.R.E.S.T.O.R.M. matrix destabilizing, the Flash and his allies find and recruit Jax to save Stein and become the new Firestorm as all three were similarly affected by the particle accelerator.
• Jax appears in the second-season premiere of Vixen.^[17]
• Jax appears in Legends of Tomorrow. In the first season, Rip Hunter recruits him and Stein to join his Legends and help defeat Vandal Savage. Despite Jax refusing and Stein bringing him against his will, the former grows to appreciate being part of a team. In the second and third seasons, Stein inadvertently changes the timeline and gives himself a daughter, who goes on to have a son named Ronnie. In light of this, Jax asks his teammate Ray Palmer for help in developing a formula to separate the F.I.R.E.S.T.O.R.M. matrix so the former can use Firestorm's power on his own and allow Stein to be with his family. In "Crisis on Earth-X", Stein is fatally injured while helping the Legends and Earth-1's heroes combat Nazis from Earth-X, but drinks Palmer's formula to save Jax from suffering his fate, sacrificing himself in the process. A distraught Jax leaves the Legends to heal from his grief, though a future version appears in the third-season finale to help them defeat Mallus.

M'yrnn J'onzz is the father of the twin brothers J'onn J'onzz/Martian Manhunter and Ma'alefa'ak. His first appearance was in Martian Manhunter (vol. 2) #3 (August 2001).^[18]

M'yrnn J'onzz appears in Supergirl, portrayed by Carl Lumbly.^[19] This version was captured by the White Martians and coerced into revealing the location of the Staff of Kolar, a psychic weapon believed to be the key to ending a war. After being rescued by Supergirl, Martian Manhunter, and Miss Martian and taken to live in National City on Earth, M'yrnn develops a form of dementia before sacrificing himself to stop Reign from terraforming Earth. In subsequent seasons, M'yrnn appears as a spirit and in flashbacks.

Rhea Jones is a fictional character appearing in American comic books published by DC Comics. She is a member of the Doom Patrol under the codename Lodestone who gained magnetic abilities in an electromagnetic explosion that killed her father.^[20] Lodestone later undergoes a metamorphosis that enhances her abilities, leaves her face blank, and moves her eyes to her chest and upper back.^[21]

• Rhea Jones makes a cameo appearance in the Batman: The Brave and the Bold episode "The Last Patrol!" as part of a poster advertising a carnival's freak show.
• Rhea Jones / Lodestone appears in the Doom Patrol episode "Doom Patrol Patrol", portrayed by Lesa Wilson as a young woman and an uncredited actress as an old woman. This version was a member of a 1950s incarnation of the Doom Patrol before they were defeated by Mr. Nobody and disbanded. As most of the team were left mentally ill following the battle, Joshua Clay became their caretaker.

Tao Jones is a fictional character appearing in American comic books published by DC Comics.

She was among the children who were experimented on by Doctor Love while they were still in their mother's womb, causing her to develop the ability to generate force fields. She becomes a member of Helix and an enemy of Infinity, Inc.^[22]

Tao Jones appears in the Stargirl episode "Frenemies – Chapter Eight: Infinity Inc. Part Two", portrayed by Andi Ju. This version is a patient at the Helix Institute for Youth Rehabilitation partnered with Kritter.

Jumpa is a fictional character appearing in American comic books published by DC Comics.

On Earth-Two, Jumpa is a Kanga, a flying kangaroo-like creature and friend of Wonder Woman who serves as her mode of transportation on Themyscira.^[23]

In Infinite Frontier, a flashback to Wonder Woman's childhood had her working to train Jumpa while riding through Themyscira. However, she is rejected and thrown into the ocean before Hippolyta rescues her.^[24]

• Jumpa appears in the Teen Titans Go! episode "Justice League's Next Top Talent Idol Star: Justice League Edition".
• Jumpa appears in DC Super Hero Girls.

The Judge is an alias used by different fictional characters appearing in American comic books published by DC Comics. Each iteration is usually depicted as a cloaked figure sporting a courtroom robe and a blindfold or sunglasses as well as wielding a mallet-sized gavel while opposing superheroes, such as Batman and the Flash.

The first version was created by Archie Goodwin and Howard Chaykin, and first appeared in Detective Comics #441 (July 1974). He was a judge in Gotham City who has a scar on his right hand, and father of Melissa Clay. After his daughter was accidentally blinded due to his corrupt dealings, the Judge blamed Batman for his problems so he kidnapped the original Robin as bait for various trap-based weapons in an abandoned summer resort. The Judge was defeated by the Dynamic Duo and turned himself in after accidentally killing his daughter.^[25]

The second version, Jacob de Witt, was created by Sam Humphries and Bernard Chang, and first appeared in Nightwing (vol. 4) #35 (February 2018). He was originally a judge from the 17th century who was tied up and drowned, becoming a blind immortal with the ability to see corruption in people's hearts. In the present, the Judge is a serial killer with a beard and white suit who uses a casino chip calling card in Blüdhaven while having several confrontations with Dick Grayson before being defeated by Nightwing and imprisoned.^[26]

Hunter Zolomon is also known as the Judge in 25th-century Central City.^[27][28][29]

An original incarnation of the Judge appears in The New Batman Adventures episode "Judgment Day", voiced by Malachi Throne.^[30] This version is an alternate personality of Harvey Dent / Two-Face who operates as a violent court-themed vigilante.