The archenemies of Guts in Berserk perform extremely depraved deeds for their own amusement. This is without mentioning the fact that every demon was once a human, who then sacrificed something or someone dear to them to the Godhand, the primary main villains of the series in general, to become that way. Due to the depressingly harsh nature of the setting, though, only a very few actually deserve to be on this list.
Wyald is the second Apostle encountered and one of the nastiest pieces of work that Guts and company meet before the Eclipse goes down. A depraved hedonist and Serial Killer, he leads a band of mercenaries made up of the worst murderers, rapists and all around scum that Midland has to offer. Wyald is introduced in the midst of an orgy, having sex with several dozen women. As he finishes with each girl, he breaks her neck, hurls her onto a pile of bodies, and then moves onto the next one, gloating about how his motto is "Excitement and Enjoyment." This sets the tone for the rest of his appearances, which show him to be a walking, breathing, raping machine. When he and his knights come across a young family, including a mother and several children, that have aided the Band of the Hawk that they have been hired to track down, they proceed to rape and murder everyone, including the children. This is followed by dismembering their bodies and carrying them naked on poles into battle with the Hawks, who are all horrified at the sight. He demonstrates an utter disregard for his men's lives, frequently triggering traps and getting them killed, solely so that he can laugh at their deaths. After transforming into his true shape, of a fifty foot tall gorilla with a three foot thick spiky penis, he attempts to rape Casca with it, bragging that she'll "feel like a virgin again" as it rips her in two. Even his own men, the aforementioned worst scum of the kingdom, follow him mainly because they are utterly terrified of him.
Griffith/Femto, Guts' ex-best friend, is the Big Bad, the Fifth Member of the Godhand and the series' definitive monster. He first establishes his cold-hearted nature after the Count, the second Apostle we see Guts encountering, calls forth the Godhand for the second time. Femto orders the Count, who is dying after having been defeated by Guts, to sacrifice his daughter Theresia — the only person left who he truly loves — for the Count to be reborn as an Apostle and keep on living or else be sent to Hell like all Apostles when they die. In flashback we discover that, even when he and Guts were friends, he was a cold-blooded narcissist, who dreamed of ruling his own kingdom no matter what it took, was willing to use his friends to commit political assassinations for him, and displays intensely jealous behaviour towards Casca and Guts. After making the mistake of sleeping with the King's daughter, he was imprisoned and put to the torture for a full year, an ordeal which destroyed whatever humanity he might have had left. Freed from prison by his True Companions, Griffith, enraged that they no longer need him to be their leader, upset that Guts and Casca now care about one another more than they do him, and unable to take the way that everyone's admiration of him has turned to pity, crosses the Despair Event Horizon and the Moral Event Horizon in a single go — he summons the Godhand and then sacrifices his entire army (which entails placing the Brand of Sacrifice on everyone he ever led, including Guts and Casca, so that they will be eaten alive by demons, and damning their souls to an eternity in Hell in the process) so that he can become Femto. And then, as Femto, his first act is to rape Casca while forcing Guts to watch, causing her intense agony through her Brand of Sacrifice (which bleeds whenever a demon, let alone a Godhand is close), driving her insane, and leaving her in a permanent Angst Coma. This act also corrupts the child that she'd conceived with Guts, turning it into a warped Fetus Terrible, which Femto eventually bodyjacks so that he might be reincarnated into the world, setting himself up as a Dark Messiah. Femto later tops himself by fusing the mundane world and the supernatural worlds together, which, in a harsh world like that of Berserk, is a very horrible sign of things to come. Defined by his selfishness, and positive that Despotism Justifies the Means, he is a figure of utter hatred to those who know his true nature.
Ganishka, the Emperor of Kushan, became insanely paranoid, when his mother tried to poison him for his younger brother to become the heir, only for the latter ones not to survive. His paranoia got to the point where his own son tried to kill him out of fear he would see his son as a threat. After accepting the Godhand's offer he has become a near-perfect example of The Caligula, which shows in mass executions, ethnic cleansing, using conquered populations as human shields or cannon fodder for his armies, attempting to rape the captive princess Charlotte and suspending women over a pool filled with hungry crocodiles, dropping thousands of pregnant women into cauldrons with stitched-together Apostles to turn the unborn babies into half-human demons that rip apart their mothers upon birth. Grandiose, megalomaniacal, and obsessed with his position as The Emperor, Ganishka revels in being as evil as he possibly can be.