Springheeled Jack was an unusual being with an obsession with killing and was named after the legendary London monster. Derek Landy has revealed that not even Jack himself knows what he is, but he is aware, and has claimed, that he is "unique". (Although it is later revealed that there were others once like him). Jack is a hideous humanoid creature who has sharp finger nails and is capable of leaping above and over great distances. He wears a top hat of sorts that will not fall off his head by itself. He haunts the roofs and streets of London at night looking for people to murder. During a live interview on "Booktopia" on Facebook, Derek confirmed Springheeled Jack would return to the series, which he did in The Maleficent Seven.
Jack later learns that Sanguine was working for Baron Vengeous who wanted to bring back the Faceless Ones. Knowing how dangerous the Faceless Ones are, Jack doesn't want them free and is furious at having been tricked. He then travels to Clearwater Hospital and engages in a short battle with Billy-Ray Sanguine. Before he can defeat him, Billy-Ray Sanguine flees from the battle. Still enraged, Jack takes out his revenge on Dusk. He defeats Dusk, unknowingly aiding Tanith meanwhile saving Valkyrie. He then leaves the country for some time.
The Revengers' Club
In the fourth book he is recruited by Sanguine and Scarab to join the Revengers' Club and is the first one to realise that Scapegrace is not the "Killer Supreme". He later takes part in the car chase between the Bentley and Sanguine's van, kicking Tanith off the roof of the Bentley. Jack later helps Dusk attack Skulduggery, Valkyrie, Ghastly, Tanith, Fletcher, Shudder and Guild with machine guns. He is arrested yet again at the end of the book by the Irish Sanctuary.
The Maleficent Seven
In The Maleficent Seven, Springheeled Jack is recruited by Tanith and Sanguine to track down the God-killers and destroy them. Jack agrees to join the club as Sanguine lies to him, telling him that in return, Tanith would tell him where he came from and other aspects of his history. Black Annis is shown to have a crush on Jack and become jealous of Sabine as Jack obviously develops a liking for her. Jack develops a crush on Sabine and tries to ask Tanith and Sanguine for advice. However, they believed that Jack fancied Black Annis and he gets annoyed as a result. After correcting them, Tanith tells him that Sabine actually likes him, even though she is repulsed by him, and decapitates Jack as he straightens in pride. His remains fall to the street below and his hat floats away in the wind. At the end of the book, Tanith explains to Dusk that the survivors will get their reward and as Jack's death was planned, she never intended to give him the information. She states: 'no-one knows where he came from'.
Magic and Abilities
Jack has demonstrated the ability to jump off of large structures and move along rooftops quickly. He can also jump out of moving vehicles without injuring himself.