Jerome Valeska was a kid born to carnival folk, raised by his snake charmer single mother. Lila Valeska was a sub-par parent, and Jerome resented her, finding cameraderie with Paul Cicero, a blind old man who was a sideshow psychic. Valeska became sociopathic, eventually murdered his mother, and then tried to hide the fact. When he was caught by the GCPD, because he was of age, he was tried as an adult and sent to Arkham Asylum, a local institute for the criminally insane.
Valeska was comfortable enough there, but his flair for murder caught the eye of criminal mastermind Theo Galavan, who jailbroke a collection of inmates, planning to use them as part of a series of staged criminal acts, as a gang called "The Maniax". Drawn to the theatrical and artificial nature of the endeavor, Valeska blossomed, becoming the leader and face of the gang.
In a plan to make Theo Galavan appear as a hero to the city on live television, Valeska held up a charity event, killed the deputy mayor, and proceeded to take Bruce Wayne as his hostage. Going off script in order to make himself look better, Galavan double-crossed Valeska by sneaking up behind him and stabbing the boy in the neck. Jerome died on the stage, laughing at the betrayal hadn't seen coming.  Jerome's corpse was taken inside a storage warehouse along with multiple other corpses. Dwight Pollard, whom used to be an employee at Indiana Hill prior to it closing down managed to learn to resurrect the dead. Dwight was also a fanatic fan of Jerome Valeska. While trying to revive Jerome he was raided by the GCPD so in a swift manner Dwight cut of Jerome's face and escaped. But little did he know that the attempt had worked and Jerome was resurrected successfully.
Jerome's corpse was brought at the GCPD morgue where he woke up at and killed a nearby police officer and took his gun. Later Lee Thompkins entered the morgue and Jerome came up behind her and asked her a few questions. Jerome was going to go after Theo Galavan who killed him but Lee explained to him that he had already died. Jerome then asked her where was his face, with her not knowing the location Jerome decided to gag her. Suddenly Channel 9 News started broadcasting and showed Dwight with Jerome's face and Jerome proclaimed that Dwight had no charisma. Jerome then took a cop car and went to the Channel 9 News Studio. After Dwight was arrested Jerome took his face and snuck Dwight in the cop car and left to the city's power plant. There Jerome stapled his face back on with a staple gun and tied Dwight up to a chair and started a broadcast as well. Jerome held a short speech and told everybody that they could kill who they wanted. Jerome then set the power plant on fire making it explode and create a blackout.
With Jerome now free, he remembers that the last thing he wanted to do before his death was to kill Bruce Wayne. Jerome and his followers then break into Wayne Manor to kill Bruce Wayne, whilst in the middle of trashing the manor, Bruce manages to convince Jerome to kill him in front of an audience in order to buy more time.Jerome and his cult then take Bruce to a theme park which is one of the places that the cult had taken over, he leads Bruce through the theme park showing him some of the cruel things he is doing to innocent people. Jerome then moves Bruce on to 'The Main Event'. He ties Bruce up and moves a circus cannon in front of him. Before Jerome could start, Alfred, Gordon and Bullock along with the strike force, stop the show and attempt to apprehend Jerome and his followers, before they have time to reach Bruce, Jerome lights the fuse on the cannon in order to kill Bruce. Bruce escapes by using staples that Jerome had put in his wrist to test him. After his escape, he leads Jerome into a mirror maze in an attempt to bring him down, Jerome places his gun on the ground and let's his confidence get the better of him, unaware that Bruce is already mildly trained. Bruce wins the fight and beats Jerome until his stapled face is hinging off of his face, Bruce picks up a piece of glass in order to kill Jerome, Jerome is constantly Psychotically laughing at him and ordering him to do it, Bruce realises what he is about to do and manages to keep his anger inside of him. He leaves a beaten Jerome on the floor and walks out. Jerome follows unexpectedly and sneaks up on Bruce and Alfred, Gordon realises and throws a punch at Jerome, this results in Jerome's entire face falling off, Gordon punches him again and his face goes flying off into a puddle. Jerome is then sent to Arkham Asylum.
- Shomanship: Having spent his life living with circus folk, Jerome has the ability to draw a crowd's attention. Emulating an MC, Jerome often gives cheery speeches or announcements of his plans.
- Immune to Pain: Due to the years of abuse he suffered from his mother, Jerome developed a tolerance for low levels of pain. This is proven as he is willing to staple his face back on and reapply stables whenever they start losing their effectiveness.
- Deception: Jerome was initially able to pose as a kind and understanding son after murdering his mother, even pretending not to care about her drunken sex life.
- He was also able to pose as a magician called the Great Rudolpho flawlessly.
- Intimidation: Because of his constant smiles and disregard for life itself, many are scared to just even be in the same room with Jerome. He is able to stab someone without so much as batting an eye, even using the victim's blood to paint a smile on Bruce's face.
- Charisma: Right after his first death, Jerome was able to inspire senseless violence and death. Upon his revival, he was able to take control of the cult that worshipped him and take over an amusement park.
- Fearless: Because he has no concern about life, Jerome isn't afraid of putting himself in situation that could potentially end with his death. In fact the first time he died, he was only upset he got betrayed.
- He played Russian roulette by himself, scaring the other into letting him lead the Maniax
- Mental Illness: Due to the abusive and neglect he suffered from his mother that Jerome suffered for years, he snapped.
- Predictable: A symptom of his insanity is his predictability. Due to growing up in a circus family, Jerome has a predilection for anything that has to do with the circus.
- Ego: Jerome loves the spotlight, often making public announcements or performing his crimes in front of an audience. He can be easily persuaded into such acts when his victims if they point out killing them in private would gain no fame for Jerome.
- Whatever he can steal.
- Whatever he can steal.
- Guns: Jerome is skilled with guns, able to shoot what he wants without wasting ammo.
- Knife: Jerome is also shown favoring the use of knives as they allow him a more personal touch when killing his victims.
- Jerome considers his mother to be a bitch, as when Gordon called him the son of one, Jerome responded "True."
- 20 Appearances of Jerome Valeska (Gotham)
- 7 Images featuring Jerome Valeska (Gotham)
- 4 Quotations by or about Jerome Valeska (Gotham)
- Character Gallery: Jerome Valeska (Gotham)