Harvey Dent was Gotham City's district-attorney and one of Batman's strongest allies until Sal "Boss" Maroni threw acid in his face, hideously scarring him. It also fractured his mental state, causing him to become Two-Face, a schizoid criminal-mastermind obsessed with the number two. His former good luck charm, a "two-headed" silver dollar, was damaged on one side during the attack that ruined half his face, and Dent has seized on it as a reflection of his half-scarred visage. He flips it to decide the fates of his victims. Despite Batman's efforts to reform his former ally, Dent is consumed by his fixation on chance and his crimes are designed to prove out his diametric philosophy.
Harvey Dent's childhood consisted of hardship. Growing up in a lower-class family, Harvey Dent was raised with an instinctive dislike and mistrust for the upper-class. These harsh surrondings resulted in him developing repressed mental-illnesses of his own, such as bipolar disorder and schizophrenia. His hard work ethic, however, allowed him to rise up to become Gotham City's district-attorney.
Sal "Boss" Maroni throws acid on Harvey's face. Gotham City district-attorney Harvey Dent was nicknamed "Apollo" by the media due to the fact that he was charming, good-looking, and seemingly untouchable. He was dedicated to his job of upholding law and order, and became one of the first supporters, allies, and even friends of Batman. At the time of his job as a district-attorney, the worst criminal threat in Gotham City was Sal "Boss" Maroni. He forged a triumvirate with Batman and Commissioner Gordon to bring the man down within the law, no matter what the cost. His slightly angrier temperament led Batman and Commissioner Gordon to develop a slight distrust for him, believing that it was slightly possible that he could be the vigilante dubbed "Holiday." The alliance ended tragically when Sal "Boss" Maroni, believing that Harvey Dent to be responsible for the death of his father, threw acid in his face during a trial. Harvey Dent was horribly scarred on the left side of his face and his left hand. Harvey Dent escaped from the hospital and descended into madness. He became obsessed with duality and opposites, and developed a second persona, the villainous Two-Face, to compliment the law & order obsessed Harvey Dent. As Two-Face, his trademark was crimes involving the number two. His obsession even shows in his clothes, which are usually composed of two halves made out of very different materials. At all times, he carries a double-sided coin with one side scarred, which he constantly flips to make any choices. Two-Face flips the coin at critical junctures: The scarred side would usually result in a crime, but the clean side would allow Two-Face to do the right thing, such as returning his loot or restrain from a murder.
After his first few encounters with Batman, Two-Face attempted to abandon all ties with his past life, including his loving wife, Gilda. This, however, proved too much for the good side of his personality, and he began attempting to visit Gilda, claiming he had regained his face through plastic surgery. Gilda, however, soon saw through the fabrication, and this unhinged Dent even more. Finally, he was apprehended by Batman, with the help of his partner, Robin.
Shortly after, a certain Dr. Ekhart performed plastic surgery on Dent's face, seemingly repairing it for good. While the facial reconstruction managed to partially heal Two-Face's fractured mind, Ekhart's assistant, Mr. Wilkins, began to place suspicion on Harvey Dent once more by committing crimes disguised as Two-Face. Batman, however, saw through the disguise and helped Two-Face clear his name. For two years, Dent led a normal life until actor Paul Sloane, scarred in the same manner as Dent had once been, was driven mad, beginning to think he was really Dent as Two-Face. Batman arrested Sloane for several attempted robberies and had his face restored, in the same manner Harvey Dent's had once been.
Dent, however, was caught in an explosion a few years later, which undid the plastic surgery and scarred his face once again. Maddened again, the revived Two-Face hired the Crime Doctor to kidnap Paul Sloane and scar the actor's face again, to mirror the transformation that had occurred in Dent. Although restored as Two-Face's twin, Sloane proved more fortunate, and had his face repaired again after being rescued by Batman. Dent, meanwhile, was bought to justice again and placed behind bars, with his renewed mental and physical scarring seemingly more permanent this time.
Harvey Dent as Two-Face.In the aftermath of the earthquake that left Gotham City in shambles during Cataclysm, Two-Face escaped custody and kidnapped Commissioner Gordon to put him on trial for his actions during No Man's Land, with Two-Face as both judge and prosecutor. Gordon played upon Two-Face's split psyche to demand Harvey Dent as his defense attorney. Dent cross-examined Two-Face and won an acquittal of Gordon.
It was also during this time that Two-Face met GCPD detective Renee Montoya. Montoya was able to reach the Dent persona in Two-Face, and was kind to him. He fell in love with her, though the romance was one-sided. After the earthquake that ravaged Gotham, Two-Face outed her as a lesbian and framed her for murder, hoping that if he took everything from her she would be left with no choice but to be with him. Montoya was furious, and the two fought for control of his gun until Batman intervened, putting Two-Face back in Arkham Asylum.
A short time later, Two-Face met the brilliant surgeon, Dr. Thomas Elliot. Although Elliot specialized in neurosurgery, he was competent enough to repair Dent's face via plastic surgery. Dent's sanity was restored, and the menacing "Two-Face" persona seemed to be gone forever. Thomas Elliot was also the villain known as Hush, and he had hoped to manipulate Dent into acting as one of his many pawns in a campaign against Batman. With renewed sanity, Dent stood by the side of law and order and betrayed Hush, catching him in enough time to save Batman's life, and shooting him into the Gotham river.
Having regained his trust, Dent was trained and conditioned by Batman to act as Gotham's primary vigilante protector when he, Robin and Nightwing all took a one-year hiatus to train during the Lost Year. When Batman returned, a series of murders occurred implicating Harvey and involving Two-Face's M.O.. When confronted on the issues by Batman, in his anger at being distrusted, the Two-Face persona resurfaced, and talked Dent into scarring his face and returning to his life of crime.
Harvey Dent has returned to his Two-Face identity and committing crimes.
In Justice League of America #13 (Vol.2), Two-Face joins the new Injustice League, headed by Lex Luther, The Cheetah, and the Joker. After the Injustice League was captured by Amanda Waller and the Suicide Squad, Two-Face was exiled to a distant planet with most of the other villains. Upon escaping with his life, Dent returned to Gotham City to reestablish himself.
Two-Face soon carved out a piece of Gotham's local mobs for his own, sharing an underworld empire with The Penguin. He appears in Battle for the Cowl: The Underground, which shows the effects of Batman's death on his enemies. A returning Black Mask, however, soon topples Two-Face's criminal empire, claiming it for his own.
Dent is forced into hiding, but ponders the possible death of the original Batman when Batman seemingly reappears, being caught on security footage to let Gotham City know that the Dark Knight lives on. Two-Face studies recent video tapes of Batman and notices that he is smiling. Dent’s henchmen notes how rare it is for Batman to grin, and Two-Face reluctantly agrees. He deduces that there is a new person under the cowl, which is in reality Dick Grayson.