Tom Miller

GCPD Sgt. Tom Miller was the leader of a ten-man undercover police squad within Arkham City.

Batman: Arkham City
When Arkham City was developed, Commissioner James Gordon, due to his attempts to question Sharp about Arkham City either being ignored directly or placed in red tape, sent ten members of the 13th precinct to go undercover into Arkham City, the leader of them being Tom Miller.

Unfortunately, as soon as he and his fellow squad arrived in Arkham City, they were exposed via an information leak and captured by the Penguin's men. Miller, alongside fellow officers Michaels and Sanchez, were held hostage within the torture room by five members of the Penguin's goons before Batman saved them. After Miller explained what happened beforehand, as well as gave him information about Penguin taking Officers Dennings and Southwold, he briefed Sanchez and Michaels that Batman saved them, so they are going to hole up the room so none of Penguin's men can either enter or leave the room, also advising them to find guns so they can hole up the room until Batman retrieves the two remaining GCPD Officers so they can get their payback on Penguin, and ordered Michaels to start a patrol and Sanchez to cover the main entrance. However, he also told Sanchez that while they do want payback, they have to do so by the book, as Gordon would have wanted that, when Sanchez implied that he would kill them if he ever encountered any of the Penguin's men. He was eventually instructed by Batman to wait ten minutes and then head over to Mr. Freeze to supply him with a charged up liquid nitrogen container for Freeze as by that point, he won't be a threat to Mr. Freeze.