Ratcatcher

Otis Flannegan used to work as a ratcatcher for the Gotham City Sanitation Department and always claimed he could train rats to attack. Flannegan was eventually arrested and spent ten years in prison after he stabbed a man to death in a street brawl. Upon his release from the Gotham State Penitentiary, Flannegan abducted the four officials responsible for his arrest and subsequent sentence. Flannegan took his prisoners to a hideout located in the sewers of the city, where he held them for five years. During this time, Flannegan developed his current criminal alter-ego as The Ratcatcher. Wearing protective equipment and using his animal training skills, Ratcatcher gathered a large mischief of rats which he used to torture and restrain his prisoners.

After five years of captivity, one of Ratcatcher's prisoners managed to escape, although the Ratcatcher sent his army of rats to kill him. The man was killed upon reaching the surface and his body was found by Batman, who followed the rats back to the Ratcatcher's hideout. Forced to confront the Dark Knight, Flannegan was outmatched once Batman got rid of all the rats and the Ratcatcher was subsequently delivered to the authorities once again.

After serving some time in prison, Flannegan escaped from his parole hearing by using a flute he had carved to control rats at a high pitched frequency. His plans for Gotham were ruined by the replacement of Batman in the end and he was once again captured.