Batman Arkham Knight

... Batman

When his parents were gunned down in front of him, young Bruce Wayne resolved to rid Gotham City of the criminal element that took their lives. He trained extensively to achieve mental and physical perfection, in addition to mastering martial arts, detective techniques, and criminal psychology. When he returned, Bruce was inspired by a bat in his ancestral home of Wayne Manor. He then became Batman who fought crime with the aid of specialized gadgets and vehicles and operated out of a secret Batcave underneath Wayne Manor. Batman led a successful twelve-year, crime-fighting career

... Bruce Wayne

born into the wealthy Wayne Family, Bruce Wayne had an idyllic childhood, although he was given a strong sense of justice by his moralistic and philanthropic parents, Thomas and Martha Wayne. After their violent murder at the hands of a mugger, Bruce dedicated his life to battling the criminal element that took their lives. He left Gotham City for many years to train to physical and mental perfection across the globe, with the aid of his butler, Alfred Pennyworth, by bringing Gotham's criminals to justice as the vigilante known as Batman.

... Alfred Pennyworth

after a varied career, was employed as the Wayne family's butler when Bruce Wayne's parents were killed. Alfred raised the young orphan and reluctantly aided him in his quest to become Batman. His many skills, ranging from cooking to medicine - made him Batman's staunchest ally, along with a formal demeanor that grounded the Dark Knight and deflected those who might otherwise suspect Bruce Wayne's true identity. Alfred showed that he cared for Bruce as his own son, one sign of this love being Batman's ally. Alfred stayed with his adopted son without hesitation and continued to aid him in his war.

Robin
... Nightwing

Raised by his parents (better known as the "Flying Graysons") in a circus, Dick Grayson was trained to be incredibly acrobatic. His parents were killed after criminals had failed to extort money from the circus. Dick was soon adopted by billionaire Bruce Wayne, who shared his secret identity and extensively trained the boy to become Batman's sidekick, the first Robin. After he aided Batman for years, Dick eventually moved on and became a hero in his own right. As Nightwing, he patrolled both Gotham City and Blüdhaven, and worked with Batman no longer as a sidekick, but as an ally.

... Comissoner Gordan

Police Commissioner James Gordon dedicated his career to cleaning up the corruption in the Gotham City Police Department, a goal he came a long way toward accomplishing. Gordon was equally tough on crime, and in the pursuit of making Gotham City safe for all its citizens, he forged an uneasy alliance with Gotham's other top crime fighter, the mysterious vigilante known as Batman.

... The Joker

The Joker is an insane, homicidal supervillain, and the arch nemesis of Batman. His white skin, green hair and blood red lips belied the chaotic nature that underlay his cartoonish appearance. The extremely intelligent self-styled "Clown Prince of Crime" had no superpowers beyond a capacity for incredible violence and a skill at creating deadly mayhem, and frequently concocted elaborate schemes to entrap his nemesis.

... Arkham Knight

The Arkham Knight was a mysterious military villain who emerged in Gotham City and was the antithetical version of Batman. He wore a militaristic "Batsuit" and had an Arkham symbol on his chest. He formed an Alliance with Scarecrow and struck a deal with Deathstroke to transform Gotham into a city of fear and end Batman

... Death Stroke

Originally a soldier in the U.S. Army during the Vietnam War, Slade Wilson was part of an experimental super-soldier program where he gained enhanced strength, agility, healing factor and intelligence. Deathstroke became a mercenary soon after the experiment and rapidly gained a reputation as one of the world's greatest assassins. Following his defeat and incarceration at the hands of Batman, Deathstroke escaped from the maximum security wing of Blackgate Prison and worked as an ally of Scarecrow and the Arkham Knight, serving as an advisor and overseer of their siege of Gotham and campaign to defeat Batman both mentally and physically, unmask him and turn Gotham City into a city of fear, specifically.

... riddler

With an obsessive need for attention and a genius-level intellect, Edward Nigma (formerly Edward Nashton) was determined to be the most outlandish of Gotham City's criminals, and concocted an elaborate series of clues and riddles around his crimes. Batman had proven to be a worthy opponent, capable of deducing the Riddler's plans, but Nigma was dedicated to creating a mystery that the Dark Knight would not be able to solve in time to save the hostages.

... Two Face

District Attorney Harvey Dent was one of Batman's strongest allies in Gotham City until Carmine Falcone threw acid in Dent's face and hideously scarred him. The wounds fractured Dent's psyche and he was reborn as Two-Face: a schizoid criminal mastermind obsessed with duality. His former good-luck charm, a "two-headed" trick silver dollar, was damaged on one side from the attack and Dent had seized on it as a reflection of his half-scarred visage.

... Robin

Tim Drake was in the audience when the Flying Graysons were murdered, and where he witnessed Batman leap to the scene. Inspired by Batman's heroics, Tim closely followed the chronicles of Batman and Robin. Eventually deducing their secret identities by using self-taught detective skills, Tim convinced Bruce Wayne and Dick Grayson - as Nightwing - that a new Robin was needed in the never-ending battle for justice.

... ScareCrow

Taunted and bullied in his youth, Jonathan Crane vowed to overcome his fears through the study of psychology and biochemistry on phobias and the nature of fear. Kicked out of the university he taught at for experimenting on human subjects, Crane adopted the identity of the Scarecrow, and armed himself with a specialized fear-inducing gas that makes a person's deepest phobia become a frightening reality. Scarecrow's ongoing reign of terror makes him one of Batman's most recurring and psychologically dangerous foes, if not the most dangerous. Scarecrow is, on certain occasions, more of a threat to Batman than the Joker.

... penguine

A brutal and sadistic crime lord, Oswald Chesterfield Cobblepot was known in the Gotham City Underworld as The Penguin who funded much of its criminal operations as one of its biggest black market manufactures. Directing his affairs from a dilapidated ship, the Final Offer, Oswald was seen as a reputable business man to the people of Gotham, but in reality, was a sadistic, mass murdering gang leader.

... Azrael

Years ago, Michael Lane was part of a program to create the ultimate crime fighter. Instead, it turned him into an insane criminal. Thwarted by Batman, Michael confessed his sins to a priest of the religious sect, The Order of St. Dumas. They recruited Michael to fight evil as their Azrael, who wore the mystical Suit of Sorrows and wielded the Sword of Sin. Azrael appeared in the Side Mission: Watcher in the Wings in Arkham City, and the Most Wanted Mission: Heir to the Cowl in Arkham Knight.