Ratcatcher

Character History
A one onetime actual rat catcher in Gotham City, 'Otis Flannegan sank into a life of crime like he sank in the sewers he was so accustomed to working in. Though he's been imprisoned numerous times in his career (he's a regular in Blackgate prison) for assault, kidnapping, and robbery (the regular line-up of Gotham's Rogues), Flannegan calls himself The Ratcatcher because of a special trait he was gifted: the ability to communicate with and train rats. While the small furry army at his control is, at first glance, a rather odd and seemingly useless gift, The Ratcatcher has used his minions to plague Gotham on more than one occasion. Imagine, if you will, a single rat. Small, weak, but strangely intelligent (just like Flannegan, who possesses an odd similarity in look to the small creatures.) But, imagine multiplying this single biting rodent by tens of thousands; a seemingly unstoppable sea of rats able to attack on a near biblical scale, all under The Ratcatcher’s control. In prison, Flannegan is able to communicate within the prison with other prisoners, and is able to smuggle items in and out, with the help of his small friends.

Even though Flannegan isn't the most devious or most powerful of Batman's rogues gallery, nor is he considered as insane, his gas mask and vermin control gear (due to the environment he works in), has allowed him to be a worthy villain among the criminal underworld.

When Infinite Crisis began, the Ratcatcher was being protected by, in addition to his rat friends, the homeless community. When he was discovered and being taken away, one of the homeless attempted to aid Flannegan, but was easily knocked aside by the arresting officers. The man turned out to be an OMAC in hiding, and the injury apparently initiated its release. The OMAC identified the Ratcatcher as a gamma level threat and vaporized him.

Batman Beyond
A character similar to Otis Flannegan named Patrick appeared in the Batman Beyond episode "Rats", and was portrayed by Taran Noah Smith. He is a deformed runaway teen who has the power to communicate with rats.

Video Games
Ratcatcher appeared as a boss in the video game Batman: Dark Tomorrow.