Warden Ranken

Warden Ranken was the corrupt warden for the prison airship Iron Heights Penitentiary.

Pre-Arkham Knight
At some point after the events of Arkham City and the lawsuits resulting from it, Warden Ranken learned about Killer Croc and was hired by the Quorum to capture and experiment on him. By October 27, Ranken and his men had tracked down Killer Croc at the Founder's Island lighthouse and proceeded to subdue him, although not before giving him minor injuries in the process. He then began experimenting on him, and realized his regeneration factor was remarkable, as it allowed the serial killer to recover from any wounds, up to and including forced amputation via a buzz saw. By October 28, his arm had fully recovered, with further surgeries being scheduled to see the full extent of his regeneration factor. On October 29, the tests were successful enough that he now intended to splice various prisoners' DNA with that of Killer Croc, hoping to replicate Killer Croc's regeneration factor, also awaiting for the recombination of the DNA to stabilize before continuing. By October 30, however, he ran into a problem with the tests: Namely, the tests had taken their toll on Killer Croc and caused him to radically mutate to become even more bestial than he already was, more monster than man, as a side-effect of the trauma induced by the experimentations via adaptation responses. In addition, the tranquilizers were no longer having any effect on the bestial serial killer, meaning he was forced to consider terminating Killer Croc. On October 31, however, around the time he was giving a video log detailing the experiments, Killer Croc proceeded to escape captivity, and managed to sabotage the engines of the prison airship. As a result, Ranken ended up trapped underneath a grate with it quickly flooding with water as a consequence of it crashing into the Gotham Bay.

Upon being saved by Batman, who had come to the airship to investigate the cause of the crash as well as attempt to apprehend Killer Croc, Ranken demanded that Batman get them out of there and leave the place to sink, though Batman was adamant in apprehending Killer Croc first. Ranken was about to protest when he was suddenly grabbed by Killer Croc and abducted by him, with Killer Croc also causing a jail breakout by the prisoners in order to ensure Batman and Nightwing cannot pursue him and stop him. However, Batman began suspecting there was more to it than the warden had let on, especially when Killer Croc just abducted him rather than just devour him then and there. He is then hooked up to a machine and demanded by Killer Croc to reverse the worsened condition, but the warden is adamant that they can't reverse it because it was a result of adaptive trauma, although Killer Croc and the other prisoners did not believe him at all and strongly implied they will torture him for the information. However, after Batman interfered, Killer Croc forced his contraption through a door to clear off enough room to fight the Dynamic Duo with his various criminals. Afterwards, Batman opened the door and released the warden's restraints, with the warden thanking Batman for stopping Killer Croc and implied that they should kill him. However, Batman, who by that point knew the truth about Ranken's unethical experimentations on Killer Croc and the various prisoners, rebuked him, telling him he was the true monster here. Ranken then demanded that he let him go, and upon being confronted with the knowledge of his experimentation, stated he won't beg for forgiveness, with Batman stating that he doesn't forgive anyway before knocking him out. He is then loaded onto the Batwing alongside Killer Croc and taken to the GCPD, where he and Killer Croc are then processed into the West Wing of the Prison facility. He is then locked up in a cell with the Iron Heights prisoners. He then tries to tell Batman that he was trying to protect this country while Batman's more concerned about protecting the prisoners while derogatorily referring to them as animals before interrupting himself when he realizes that his cell is right next to Killer Croc's cell and begs Batman to let him out of there as he doesn't want to be next to Killer Croc.

Batman then demands to know the names of who specifically hired Warden Ranken for experimenting on Killer Croc, as he had learned about Quorum's involvement in his capture and experimentation of Killer Croc. Ranken, however, smugly tells him that he isn't concerned with the Caped Crusader's wants before telling him to run along. Batman vows that he'll talk eventually as "they always [talk]." He then smugly tells the Dark Knight that he loves invalidating a flawed hypothesis due to his being a scientist. Killer Croc later asked whether Ranken will ever get justice, with Batman saying he'll get justice, although Killer Croc is not satisfied, as he wanted to kill him as payback for what he did to him.

Trivia

 * Ranken was only identified by name once, by Prison Officer Burfitt, when explaining why they had held Killer Croc prisoner and alluding to his experiments on him. He is only identified as "Warden" in the subtitles, even AFTER the player completes the mission.
 * If the player completes the mission after the main storyline, he will acknowledge Batman and Bruce Wayne as being one and the same, and even attempt to do a psychological evaluation for Batman's motives only to declare him insane.