Gillian Loeb was the Gotham police commissioner. When Thomas and Martha Wayne were murdered, Loeb informed their son Bruce that the perpetrator had been apprehended.
Years later, Loeb was investigating the arrest of Carmine Falcone, after his men claimed that a giant bat had attacked them and tied up Falcone. He told his police officers to make their priority the arrest of the vigilante who did this, despite protests from James Gordon.
Later, the Joker was terrorising Gotham and named Loeb as a target. Gordon came to Loeb's office to warn him of the danger, but Loeb's solution was to take out some whiskey for a drink. Gordon realised that the Joker's men would have had access to Loeb's belongings in order to get a sample of his DNA, but too late worked out that Loeb's glass had been poisoned. Loeb drank from the glass and collapsed, smoke rising from the vessel. James Gordon was later promoted to commissioner in Loeb's place.