Harvey Dent

Harvey Dent was the former district attorney of Gotham City who received brain damage by a mobster's acid. He then became a bloodthirsty, eccentric and homicidal maniac who called himself Two-Face, who had a penchant for using a coin and flipping it to determine all of his decisions and his actions. He teamed up with The Riddler to help him with his scheme.

While fighting Dick Grayson, Two-Face panicked and tried to flip his coin, but he stumbled and fell onto a pit of watery spikes. Two-Face then died.

Exposing Grissom front companies
Harvey Dent worked closely with Commissioner Gordon to find evidence of font companies owned by Carl Grissom and members of his syndicate. During this time Mayor Borg pressured Dent to find all the answers with immediacy, which only worsened with the emergence of Batman and the Joker. Dent and his allies failed to make the streets safe in time for the 200th Anniversary Parade.

Bat-Signal press conference
Dent read a letter from Batman to the citizens of Gotham at a press conference after the Joker's demise.

Scarred by Boss Moroni
While Dent questioned mob boss Sal Moroni in court, Moroni managed to retrieve a hidden flask of acid and threw it on Dent. Batman became aware of that plot, and ran through the courtroom to save Dent, but arrived too late. The acid splashed against the left side of Dent's face, and horribly disfigured it, while the right side was protected by his notepad.

The acid burned far enough through Dent's head that part of his brain was damaged, and made him psychotic and homicidal. He developed a second personality, called "Two-Face" and would refer to himself in the plural. Dent was eventually arrested and committed to Arkham Asylum.

Escape from Arkham Asylum
Two-Face escaped from his cell on the second anniversary of his arrest, and his escape was discovered by Dr. Burton, who then contacted the GCPD. Two-Face and his thugs robbed the Second Bank of Gotham. They took hostages and looked like they were going to get away when Batman intervened and stopped the robbery. Two-Face trapped him and a guard inside an acid filled safe, but Batman escaped and saved the horrified guard. Batman pursued Two-Face by boarding his helicopter. However, Two-Face escaped before he crashed his helicopter into the Statue of Justice over Gotham Harbor.

At his new hideout, which had decor split in half like his personality, Two-Face had two molls, Sugar and Spice, who worked for him. Spice favored his 'dark', scarred side, while Sugar favored his 'good' side.

Murdering the Flying Graysons
Two-Face traveled to the circus looking for Batman. The circus held a fundraiser that was attended by Gotham's elite, and Two-Face concluded that the odds were excellent that at least one of them knew the Dark Knight's identity if they weren't Batman himself-, and he threatened to blow the place up unless his enemy turned himself over (although the subsequent riot in the circus prevented Bruce Wayne from obeying his order). Two-Face was responsible for the origin of Robin because, when the Flying Graysons tried to stop him, they were all killed by him apart from Dick, the youngest Gray son, who went on to join Batman as Robin after he stopped his bomb.

At his hideout, Two-Face met Edward Nygma, who adopted the mantle of the Riddler, where Two-Face initially wanted to kill him for invading his lair, but Riddler stated his case, and Two-Face decided via coin flip whether he killed or allied with him. After his coin landed on heads, Two-Face stole enough money to fund Nygma's company, and the two gained knowledge through the Box and discovered Batman's true identity at Nygma's party. Following that, they traveled to Wayne Manor and the Riddler destroyed the Batcave. Two-Face, on other hand, had his henchmen attack Bruce and Dr. Chase Meridian while he flipped his coin, which kept landing on the good side, and prevented him from doing any wrongdoing. As soon as the scarred side came up, Two-Face fired his pistol at Wayne, which grazed him in the head. Two-Face wished to finish him off, but the Riddler intervened, then they left, kidnapped Dr. Meridian, and left behind a riddle.

Fighting Dick Grayson at Claw Island
At Claw Island, where Two Face hid, Batman and Robin got separated. Robin had the opportunity to kill Two-Face, but didn't want to be like him. Two-Face used that to capture Robin. Two-Face and the Riddler then tried to make Batman choose between Chase and Robin but Batman destroyed The Box, which permanently defeated the Riddler, and saved them both. Two-Face showed up, and was poised to kill them, but Batman reminded him of his coin. Two-Face flipped his coin to decide if he would shoot Batman, but Batman tossed a handful of identical coins into the air. Two-Face panicked and tried to find his coin but stumbled and fell into the pit on a watery bed of spikes. His exact coin then fell good side up into Two-Face's open palm before he sunk underwater, dead.

Legacy
Three years later, when Bane broke into Arkham Asylum's storage room to get Mr. Freeze's suit, Two-Face's unique costume was glimpsed hanging on a shelf, but it was unclear if that meant that he had survived his fall and was captured or if it was simply a costume that he left behind during his last escape.