Ever since his creation at the tail end of the 1930s, Batman has accrued quite a massive and terrifying rogues gallery featuring many colorful characters. What separates Batman's villains from the likes of Superman's more cosmic rogues is that they're far more human, giving many of them chances to see the light.
Regardless of the humanity of certain Batman villains, many of the psychos who have called Arkham their home at one point are outright monsters that are completely beyond redemption. In fact, The World's Greatest Detective's greatest nemesis is one of the most evil individuals in all of fiction.
Redeemable: Mr. Freeze
Mr. Freeze initially was just a generic bad guy, but after Batman: The Animated Series radically reimagined him as a tragic figure, the comics soon followed suit. Perhaps in another life, Victor Fries could have been eligible for a Nobel Peace Prize, but an unfortunate accident turned him to the dark side.
Despite doing some fairly reprehensible things, Mr. Freeze's longing for his frozen wife Nora paints him as sympathetic, thus making it possible for him to be redeemed. It may never happen, but a face turn for Freeze is always in the cards.
Too Evil: Ra's Al Ghul
Time can soften someone, but in Ra's Al Ghul's case, it's made him even more of a stone-cold killer than he already was. Though his objective seems noble, his goal to completely wipe out all life on the planet is the kind of thing he can't come back from.
Of all of Batman's irredeemable foes, Ra's Al Ghul is the saddest case, as his wisdom, intellect, and unique relationship with The Dark Knight could work wonders for the superhero community. Alas, Al Ghul's commitment to his sinister goals makes it hard for him to fight alongside the man he respectfully calls "Detective."
Redeemable: Two-Face
Though it waxes and wanes, with the likes of The Riddler and The Penguin challenging for his spot, Two-Face is seen as the second greatest Batman villain by many a fan, which is rather fitting. But unlike The Caped Crusader's greatest foe, Two-Face is much more sympathetic.
Harvey Dent, once Gotham's noble District Attorney, was driven mad when the left side of his face was scarred, so his heroic past could offer a glimpse at his path towards redemption. Most stories that feature a cured Two-Face see him return to the courtroom in some capacity, so he could become Gotham's true savior once again if given the chance.
Too Evil: The Court Of Owls
Sure, a lot of these baddies have been around for a while, but youth doesn't always entail a lack of experience. Created for The New 52 relaunch of Batman by Scott Snyder and Greg Capullo, The Court of Owls is a secret society of elites that sends hitmen known as Talons to kill whoever they see fit.
Ruining Gotham City since its inception, The Court of Owls' ruthlessness is so widespread that they have an eerie nursery rhyme to their name. The Court of Owls have been the boogeymen of Gotham for centuries and that isn't going to change now.
Redeemable: The Riddler
The idea of The Riddler turning good may seem utterly baffling to most fans, as his name is infamous for villainy as well as frustration. Those who are confused by this notion are likely sleeping on Paul Dini's run on Detective Comics.
For a very brief period of time, The Riddler worked as a private investigator after a blow to the head rid him of his incessant need for riddling. Though it didn't last long, it was a fun period for The Riddler and one that desperately needs to be revisited.
Too Evil: The Mad Hatter
Often disregarded by fans because of his admittedly silly gimmick, The Mad Hatter is a lot more baleful than most people want to give him credit for. A villain who is obsessed with the writings of Lewis Carroll, Jervis Tetch is a small man with big ambition, but that ambition makes it difficult for him to turn good.
Much like Mr. Freeze, The Mad Hatter started off as a lame villain whose schtick was the one thing that separated him from the pack, but time gave Mad Hatter a more sinister edge. Using mind control tech to get people to do his dirty work, Hatter is the kind of person who clearly draws pleasure from the suffering of others.
Redeemable: Poison Ivy
With Harley Quinn currently in the midst of a full face turn and Catwoman being a pure anti-hero at the moment, Poison Ivy is the only member of the Gotham City Sirens that hasn't fully turned. With that being said, she certainly has what it takes to make the jump.
Currently, Ivy's relationship with Harley Quinn has evolved from womance to romance, so it's only a matter of time before Harley's heroic aspirations pull Poison Ivy into the hero game. Also, Ivy has served on hero teams in the past like The Bird's Of Prey, so she has ties to two of the biggest hero teams in The DC Universe.
Too Evil: The Joker
The Joker is one of the most famous villains in the world, with his relationship with Batman being as beloved as it is toxic. The Clown Prince of Crime has tormented The DC Universe for decades, with his insane brand of evil only growing broader with the passage of time.
The list of Joker's near-unspeakable actions is legendary. The murder of Jason Todd, the crippling of Barbara Gordon, the kidnapping and torture of Commissioner Gordon, it's all canon and all horrible. The Joker is a monster, the only redemption he'll get is when someone finally puts him out of everyone's misery.
Redeemable: Clayface
Basil Karlo, the first Clayface, is a bit of a cheat, as he has been a hero previously. In James Tynion IV and Eddy Barrows' acclaimed Detective Comics run, Clayface was brought into the Bat-Family where he had a special friendship with Cassandra Cain.
Sadly, after being manipulated into attacking his friends, Karlo was seemingly murdered by Batwoman only to be revealed to have survived, leaving Gotham for a while. While a later digital tale portrayed him as a baddie once more, that story may not be canon, so he could return to the fold at some point.
Too Evil: Scarecrow
While The Joker is the most prominent hopeless cretin that's plagued Batman's life, Scarecrow has an edge to him. Though Joker's violent madness does a good deal to explain his actions, Scarecrow is a lot more sane but just as sinister as The Alabaster Jester.
According to Dr. Stephen Kellerman in Batman: Arkham Asylum, Scarecrow may not be insane, instead, he is so evil that it makes him look insane. Based on his horrific actions in the comics, Scarecrow has proven just how right that assessment is.