Jessica Jones season 3 sees Marvel's top private eye face a whole new nemesis - an insane serial killer lifted straight from the comics, the Foolkiller. The first season of Jessica Jones was one of the best of the entire Marvel Netflix range, in large part because of the electrifying dynamic between Krysten Ritter's Jessica Jones and her arch-foe, David Tennant's Kilgrave. The show was a tense psychological drama, taking full advantage of Kilgrave's ability to control the minds of others.

Jessica Jones season 2 wasn't quite so well-received, in large part because it lacked a real antagonist. For season 3, showrunner Melissa Rosenberg has taken the series back to its roots in psychological horror, and she's done this by bringing Jessica face-to-face with Foolkiller, a serial killer whose ruthless genius is beyond anything even Jessica has encountered before. In a world of super-soldiers and Asgardians, Gregory P. Sallinger is a truly terrifying thing; a twisted sociopath whose greatest ability is his intelligence.

Related: A Complete Timeline Of Netflix's Marvel Cancellation

But just who is Gregory Sallinger, and how has Marvel Television adapted the character from the comics? Here's your essential guide to Jessica JonesFoolkiller.

In the comics, Greg Sallinger was the second super-villain to take up the identity of the Foolkiller. The original Foolkiller, Ross Everbest, was a religious maniac who believed he'd been chosen by God to kill anyone he branded a sinner. Everbest invented a powerful weapon, a "purification gun" that disintegrated people with a single shot; he donned a flamboyant, Zorro-like costume, and began a campaign to kill anyone he deemed to be a fool. He tended to give his victims a warning card; "Foolkiller / e pluribus unum / You have 24 hours to live. Use them to repent or be forever damned to the pits of hell where goeth all fools. Today is the last day of the rest of your life. Use it wisely or die a fool." The Foolkiller chose to pursue the Man-Thing, and died in the attempt to destroy the creature; in a twist of irony, his soul was condemned to eternal torment in Mephisto's Hell.

Greg Sallinger was inspired by the tale of the first Foolkiller, and decided to take up Everbest's crusade - albeit with a twist. Where Everbest believed a fool to be a sinner or dissident, Sallinger branded anyone who lacked "poetry in their soul" a fool. He was as likely to attack a mailman as he was a pimp, and incredibly he decided to cross wits with a superhero team, the Defenders, but was outwitted by Hellcat and Valkyrie. He's been a recurring background villain over the years, sometimes positioned as a twisted antihero, and he's particularly notable for one encounter with Spider-Man; Sallinger realized that only a fool would believe he could beat the webhead, and thus attempted to kill himself. Fortunately Spider-Man stopped him.

More recently, Foolkiller has been reinterpreted as an unexpected agent of S.H.I.E.L.D., using his degree in psychotherapy to counsel would-be supervillains who S.H.I.E.L.D. viewed as high-risk, such as Red Skull fanatics who liked to walk around with their faces caked in blood. Those he couldn't persuade to change, he killed. Ironically, Sallinger was unaware he was himself being played for a fool by rogue S.H.I.E.L.D. agents who were working to their own agenda.

Related: The REAL Reason For Captain America: Civil War Revealed By Marvel TV Timeline

In the comics the Foolkiller has always been something of an absurd figure, played for dark comedy. Jessica Jones turns that on its head, using the idea as the inspiration for a dangerous and psychotic serial killer. The Marvel Netflix version of Gregory Sallinger is a ruthlessly intelligent man without a trace of empathy. He was bullied and abused as a child, and as a result grew up distanced from the rest of the world, viewing others as inferior to himself. Sallinger loves knowledge, and is proud of the fact he's successfully completed a number of doctorates, ranging from Psychology to Marine Biology.

Sallinger's personality is essentially defined by a twisted combination of pride and insecurity. He's been murdering people since he was a teenager; sometimes those he views as inferior, sometimes those he sees as a threat because they are naturally "gifted" in some way and he just doesn't see that as fair. Sickeningly, before he murders a person he likes to use his knowledge of psychology to strip them of all their illusions about themselves, psychologically torturing them, and he photographs their faces the moment before he kills them.

Marvel Television's version of Sallinger is a fascinating one, not least because he's clearly the kind of person who'd be threatened by the existence of superheroes. Superheroes, after all, are stronger, faster, and smarter than anyone else; and, what's more, many of them acquired their powers by accident, meaning their gifts are once again "unfair." It doesn't take long for Sallinger to begin a deadly game of cat-and-mouse with Jessica Jones and Trish Walker, a.k.a. Hellcat. Where the Foolkiller of the comics wears a costume and uses a disintegration gun, this version of Sallinger relies upon his abilities as a wrestler and his proficiency with knives. Jessica will pay a fearful price to best him.

Marvel Television has recruited American actor Jeremy Bobb to play Foolkiller of Jessica Jones season 3. Bobb is best known for Manhunt: UnabomberGodless, and Russian Doll; he also played circus performer Owen Lloyd in Gotham, meaning he's now worked for both Marvel Television and DC Entertainment. Bobb told Marvel he was drawn to play Sallinger because he considered him to be a fascinating, complex villain.

"There’s an opportunity to show different faces of this person, and I like to play a character that I have to shift and shape a little bit, even if it’s just a character that isn’t shifting, but I have to play it. I really enjoy that. But when the character does it himself, it’s pretty cool. It’s subtle for him. I’m not turning into a creature or anything, but that’s just interesting that he carries himself with one set of people one way and a different way with others."

Related: Why Jessica Jones Was Cancelled By Netflix (Before Season 3)

Over the years, Marvel Netflix has developed a strong reputation for top-rate casting; indeed, Jessica Jones season 1 would have been nothing without the choice of Ritter as Jessica and Tennant as Kilgrave. In the case of Greg Sallinger, Bobb is very different to the charismatic figure from the comics; but that makes his portrayal all the more chilling, and the cat-and-mouse dynamic between Sallinger and Jessica stands at the center of Jessica Jones season 3. With Bobb playing the part, the Marvel Netflix shows end with style.

More: Jessica Jones Season 3 Review: A Final Season Best Experienced On Fast Forward

Jessica Jones season 3 is now available for streaming on Netflix.