A hero is only as good as his villains, and thankfully Batman has the absolute best selection of rogues of any DC hero. There's the egotistical Riddler, the tragic Two-Face, and of course the maniacal Joker, among others. These crazy Batman villains have helped cement the Dark Knight as a legend, and some of them have proven they're strong and complex enough to carry their own comic book series, too.
Below is a list of some of the worst things Batman villains have ever done. Some are grand, doomsday-esque scenarios, while others are more personal vendettas against people who messed with the wrong villains. Either way, all these villains are certifiably insane - and the psychotic things some of them have done definitely prove that fact.
Hush feels like a villain right on the verge of greatness. He's one of Batman's deadliest foes - on both a physical and personal level - yet he's not famous enough to stand among the Joker, Two-Face, Penguin, or any of the other heavy-hitting Batman villains. That's not from a lack of despicable acts, though.
In early childhood, Hush was named Tommy Elliot, and he was extremely close friends with Bruce Wayne because they both came from wealthy families. Tommy hated his abusive father and passive mother, so he cut the brake lines of his parents' car, an act that led to their deaths and sealed his fate as a future villain. He has been part of a few of Batman's most devastating storylines, including Heart of Hush, which saw Hush come back to exact his revenge on Batman after he learned his true identity. To really hurt Batman on an emotional level, Hush hunted down Catwoman and proceeded to cut out her heart. He left her left clinging to life and Batman fell into a deep despair as a result.
While he may be flamboyantly dressed, Flamingo is easily one of the most cold-hearted, unfeeling members of Batman's rogues gallery. After he was brainwashed by the Mob into being the perfect hitman, he murdered his whole family to eliminate his connections to the world.
As if that wasn't enough, Flamingo (real name Eduardo Flamingo, which is insane) regularly eats the faces of his victims. Not, like, for any particular reason. He doesn't think it'll make him stronger or give him the ability to take on their appearance, or whatever. In Batman #666, it's made apparent that he just really, really likes to eat people's actual faces off of their f*cking heads.
Choosing the most shocking thing the Joker has ever done is really an impossible task. He's just committed so many heinous acts that singling out any one as the worst isn't easy. One of his most heinous acts, though, happened when Brian Azzarello reintroduced the character in his graphic novel, Joker.
The Joker resumed his mantle as the Clown Prince of Crime after spending a long time in Arkham Asylum. Upon his release, he found one of his henchmen, Monty, had started to make a name for himself in the Joker's absence. This might have been okay on its own, but the Joker then learned that Monty hired his beloved Harley Quinn to dance at his strip club. This sent the Joker into a rage. One that led to this scene, where he skinned Monty - alive. The Joker then pushed Monty out onto his own strip club stage so he could get a taste of what it was like to be seen as nothing more than a piece of meat. The scene was gory, disgusting, and absolutely shocking.
The Joker has done some deeply, deeply horrific things to the Bat Family. While some of the members of Batman's rogues gallery are more campy than sinister, those who underestimate the Clown Prince of Crime usually wind up dead - or worse. In the landmark story arc Batman: A Death in the Family, Jason Todd learned that lesson the hard way.
The Joker bludgeoned Todd to death with a crowbar (at the behest of an audience poll, because people are terrible), leaving Batman to find the bloody, mangled corpse of his young ward in the wreckage of a collapsed building. Although Todd later returned to life (a version of Superman punched a hole in reality, it was a whole thing), his death stood out as the Joker's most merciless act for years in the DC continuity.