Commissioner Gillian B. Loeb is a corrupt GCPD commissioner.
Gillain makes his first appearance in Frank Miller's Batman: Year One as the corrupt Gotham City Police Commissioner who hired Lieutenant James Gordon. Loeb surprisingly liked Batman's first appearance, calling off any units sent by Gordon to capture him, as the Dark Knight gave the people "false" hope. Loeb liked the Caped Crusader until he crashed a party Loeb was attending and tied up Loeb's favourite criminal, Falcone.
The enraged Loeb turned armies of officers against the Bat, but his unsuccessful arrestings resulted in several failed attempts to bring the vigilante to "justice". Later, Batman, Harvey Dent, and Gordon revealed to the public of Loeb's workings with Falcone's mob, so the corrupt officer was replaced.
In Batman: Dark Victory, Loeb sided with the Hangman, where Loeb was eventually killed by his own partner.
Batman Begins and The Dark Knight
Loeb appears as a supporting character in Batman Begins, where he was portrayed by Colin McFarlane. He first appears at the beginning when he informs a young Bruce Wayne that they captured Joe Chill, his parent's murderer. However, decades later, Loeb ordered a large task force to arrest the newly arriving Batman due to the fact vigilantism is illegal. Later, during Ra's al Ghul's attack on the city, Loeb attempts to figure out the situation on Arkham island and informs Gordon that all the riot police were unavailable. He also most likely promoted Gordon from Sergeant to Lieutenant for his heroics during the attack.
Loeb is portrayed as much more of an honest cop in the films than he is in the comics, despite the fact that he is at odds with Batman due to his vigilante methods.
In The Dark Knight, Loeb is killed when he drinks a glass of poison-laced alchohol planted by the Joker. A city-wide funeral is later held in his honor, but the Joker and his men strike at this as well, disguised as policemen, in an attempt to kill Mayor Garcia. They fail in killing the mayor, but they supposedly kill Lieutenant Gordon, who was later revealed to be alive, but faked his death in order to protect his family. Gordon takes Loeb's place as Police Commissioner.
Batman: Arkham Origins
Loeb appears in the Batman: Arkham Asylum prequel, Batman: Arkham Origins, as, yet again, a corrupt police officer
in charge of the GCPD. However, he was betrayed by The Joker (who was impersonating Black Mask) where Loeb was thrown into Blackgate Prison's execution chamber (which was meant for the Calendar Man) and was killed via gas before a young Batman could help.
Later in the game under the influence of Copperhead's neurotoxin, Batman hallucinates Loeb chastising him for not helpinng him, representing Batman's guilt over not being able to save the corrupt commisioner before he was murdered.