Gillian Loeb is the corrupt Commissioner who takes a cut of a criminal drug racket. In the first issue, after Jim Gordon refuses to take a bribe, Commissioner Loeb lets detective Flass and other officers attack Jim Gordon to send a message and warn him that next time they're going after Jim's pregnant wife, Barbara.
In the third issue, Batman is trapped inside a building that has been ordered to be demolished by Commissioner Loeb. After the building is destroyed the Commissioner sends Brenden and his SWAT, who he uses as his own personal hit squad, to find and kill Batman. Batman makes a escape from the building using a device that uses ultrasonic tones that attracts bats from the batcave and in a cloud of bats manages to slip the Commissioner who was pursuing in a helicopter.
In the last issue, Batman takes down a drug dealer named Jefferson Skeevers and makes him turn himself in and reveal that Flass is a part of Gotham's drug operation. In an attempt to stop Gordon from coming forward with the prosecution, Loeb tries to blackmail Gordon with pictures of Gordon and Sgt. Essen kissing but it doesn't work. In a last ditch attempt Loeb orders that Barbara Gordon and their new born son be kidnapped till the charges are dropped. The plan is foiled by Gordon and Bruce Wayne who wasn't wearing a mask but due to Gordon losing his glasses in the fight, he couldn't tell who it was. Flass was put put on trial and found guilty but after two weeks in jail came forth with information Commissioner Loeb such as dates and times of certain activities. Loeb was not convicted but was forced to resign from his spot as Commissioner of GCPD.
Loeb pays a visit to Jim Gordon after the first Hangman murder and warns Jim that if he doesn't get the situation under control that the city council was considering Loeb for the job. Later the Hangman Killer breaks into to the retired Commissioner's house and kills Loeb then hangs him from a chandelier.
Loeb is once again the commissioner in Detective comics #25 and is very much still a crooked cop, the Black Mask gang has struck again and theirs no rest for the wicked or so for the great Lieutenant James Gordon, when no one on the force will help him, so he goes to Loeb asking for help and he sets up a partner Henshaw who also is corrupt and leads Gordon to his death by setting up a buyout with the Black Mask Gang, so it seem but Batman came swooping in just in time to save him, Gordon makes his way back to G.C.P.D. headquarters and hits a big knockout punch to Henshaw and slapped down a file on all the corrupt cops and the Black Mask gang, but one cop couldn't let that happen so he points a gun at Gordon but Bullock get a knockout hit with is gun and days later every corrupt cop that had anything to do with the Black Mask gang is dead and this strengthens the bond between Batman and Gordon. Gordon can see the empty sadness inside of Loeb and he knows "He'd lost control of Gotham and its police and some time ago, he'd given up the fight." Loeb is now on the hunt for Batman when the Riddler gave the G.C.P.D. tactics on how to defeat Batman and also gave the location of where Batman is, only by the help of Gordon does he survive.
Batman: Arkham Origins
Loeb appears in Batman: Arkham Origins as the corrupt commissioner of the GCPD. He is captured by Black Mask early in the game and murdered in a gas chamber, Batman being to late to save him. He is later shown in an illusion Batman is having when Copperhead poisons him, yelling at Batman because he was to late to save him.