Batman Arkham Knight " Dr. Kirk Langstrom, AKA Man-Bat ".

" My life hasn't exactly gone the way I planned. I have a lot more to offer the world than losing my mind and trying to eat Batman... I was a respected scientist once... I thought, perhaps, if I could make some sense of this strangeness, they'd respect me again? " Man-Bat

Dr. Kirk Langstrom is the inventor of the infamous Man-Bat Serum, a special formula that has the ability to turn the user into a hideous bat monster, the Man-Bat. Though he originally created it to help the deaf and blind, because of its temporary side effects, multiple people have taken advantage of it, including Langstrom himself, often in the name of vigilantism. However, because the user becomes almost feral with its use, Langstrom has acted as both an ally and enemy to Batman.