Gillian B. Loeb was the corrupt Commissioner of the GCPD during Batman's early years as Gotham's caped crusader. While in charge of the city's police force, Loeb was every bit as much of a mob boss as the criminals he vowed to bring to justice. Using the GCPD as little more than a secondary gang for the city's various crime syndicates, particularly those who paid the most, Loeb used his lofty position, considerable resources, and political connections to further his own standing and, by association, the criminals who could reward the corrupt commissioner the most.
During a particularly snowy winter, Loeb collaborated with the city's most powerful crime boss, Black Mask, to cement his political control over the entire city. Unfortunately for Loeb, his corrupt nature and affiliation to Black Mask made him a target to the emerging criminal mastermind and mass-murdering psychopath, known simply as the Joker, who sought make his own name and carve a legacy for himself in the criminal underworld as its most iconic villain.
His resulting death at Joker's hands led to a massive power vacuum that spread throughout the GCPD and Gotham's criminal underworld, shaping the future of the city to one governed by much more ethical political individuals but also regularly attacked by more outlandish and theatrical villains motivated to counter Batman's methods.
Loeb had ties with Black Mask and ran operations with Sionis in consideration. He once tried to have the police make false accusations of then-Captain James Gordon, as well as a plan that regarded "beating sense" into Gordon via Detective Arnold Flass, but those fell through, and Loeb considered having Gordon murdered, although Sionis talked him out of it.
Eventually, Loeb had Harvey Bullock try to dig up any dirt on Gordon, as well as implied an order to set up a honeypot trap. Loeb also had one of his protégés on the force, SWAT Lieutenant Howard Branden, meet up with an individual with the handle "Façade" to gain illicit material, and eventually ordered Branden to kill Batman after Branden had reported that several of their men had called in sick due to fear of the then-recently emerged masked vigilante, as he couldn't lose the amount of power that he had gained in Gotham City via City Hall over "cold feet," before he took a call from Warden Martin Joseph.
Loeb held a press conference on Christmas Eve that regarded the impending execution of Julian Day after he was arrested. Behind the scenes, Loeb had manipulated Warden Joseph into having intern Harleen Quinzel, redact her psychological profile on Day, as it was implied that he was legally insane, in order to allow the corrupt legal system in Gotham to execute him. While it was strongly implied that Day was indeed insane, Loeb intended to execute him in order to obtain massive support from City Hall and Gotham's Citizens in order to further his own political agenda and lust for power and control.
In exchange, Quinzel was allowed to conduct psychological evaluations on all new inmates of Blackgate Prison to determine their mental stability, a course of action that ironically enabled the Joker to have another pawn in order to break out later during the long and brutal night. During the course of his press conference, Loeb dismissed any questions from press after one of them had inquired the rumors that the GCPD wasn't actually responsible for Day's apprehension (the implication was that Batman was responsible instead).
That same night, Blackgate was broken into by Black Mask's Henchmen, and Loeb was taken hostage. Loeb questioned whom he thought was Sionis about his actions. Black Mask replied that things had changed, and that he was starting with a new slate: one that Loeb wasn't on. A protesting Loeb was then thrown into the Gas Chamber, where he died from the poisonous fumes. Batman, after he was poisoned by Copperhead at the Steel Mill, briefly hallucinated Loeb blaming him for not saving him and accused him of not being a hero, which implied that Batman had still felt some guilt for not saving Loeb in time despite the former Commissioner's corrupt nature.
Shortly after his death, Loeb's corrupt nature and criminal actions within the GCPD, alongside him on the payroll of Black Mask and presumably other criminal kingpins, was revealed to the public and resulted in immense outrage by the citizens, and also eventually resulted in severe protests that lasted up to six days in both North and South Gotham.
The notorious amount of corruption that Loeb represented was remembered, especially by the criminal element of Gotham, as far off as a decade later, where a street thug, during Scarecrow's terror threat, commented that one of the positives of Loeb's time as Commissioner was that, unlike Gordon, he could be paid off, although that same thug was unaware that Loeb was long dead.
- Commissioner Loeb: Gordon. He's so clean, I sometimes think he does it just to lord his integrity over the rest of us!
- Black Mask: Easy, Gillian
- Commissioner Loeb: I'm telling you, Roman, it's time we take Gordon off the payroll - permanently.
- Black Mask: That's enough, Gill! A cop like Gordon is good PR for the PD. We get him under control and he could be even more useful to us.
- Commissioner Loeb: Control? It would be easier to send my men to beat some sense into him!
- Black Mask: Like Detective Flass? That approach has already failed. Find a way to put a collar on the man, and it will be that much easier to tighten the leash.
- Commissioner Loeb: And how do I do that?
- Black Mask: Not my problem, Gillian - that's what I pay you for. Gordon is a man of principles. Work on those.
- Harvey Bullock: Whaddya want me to do? Become his confidante? Gordon trusts me about as far as he can throw me!
- Commissioner Loeb: So, not very far at all?
- Harvey Bullock: Yeah, I get it. I'm a big guy.
- Commissioner Loeb: You're a fat slob who needs to start earning his keep! Now, men like Gordon have a weakness for a certain type of woman. They call it the 'Lancelot Syndrome' or some such crap.
- Harvey Bullock: What are we talkin' about here? You want me to set up a honeypot?
- Commissioner Loeb: I'll leave the details to you. Find me some dirt - and try not to make a mess of it!
- Commissioner Loeb: What do you want me to do? Hold your hand?
- Branden: This 'bat-guy' has some of my men really spooked. Some of 'em are even calling in sick.
- Commissioner Loeb: Then fire their asses! I don't have time for fence-sitters! Soon, I'll have all of city hall in my pocket, and I'm not about to lose it over some cold feet.
- Branden: So, what should I do about it?
- Commissioner Loeb: Cement shoes? You figure it out.
- Secretary: Commissioner Loeb?
- Commissioner Loeb: Yes?
- Secretary: Warden Joseph on the line.
- Jon Polito previously voiced Loeb in the Animated Adaptation of Batman: Year One.