Spoilers below.
- The execution scene in the first episode. Doesn't help we can see the doomed man's tears soaking through his hood. The crowd shouting "KILL! KILL! KILL!" is also distressing, as their outrage at an unrepentant murderer being released wasn't enough to stop their bloodlust.
- The Count tossing a bag full of the ransom money demanded by Luigi Vampa's gang at their messenger is a dose of black humor. Cut to the figure of the Count silhouetted in the shadows with his eyes barely visible as he calmly demands Albert's freedom with thinly veiled menace, and one can't help thinking he really is a vampire... And then...
- The Count confronting Luigi Vampa during Albert's rescue is both awesome and nightmare fuel mixed into one. As if Gankutsuou's trademark eyes glowing under the Count's hat weren't scary enough, the Count's own eyes are glowing RED while the rest of him is silhouetted once again in shadows. And then Luigi makes the mistake of hurling his dagger at the Count, expecting him to die from the wound he undoubtedly gives him, only for the tables to turn. The Count's eyes are no longer glowing as he calmly pulls the dagger out of his chest - with the wound undoubtedly healing thanks to Gankutsuou's power - and stalks towards the bandit leader with a sadistic slasher grin on his face. He points out that Luigi can't kill him so easily - if at all - and closes in on the now terrified man with the pointed tip of the dagger slowly nearing his eye....
- Upon the Count's arrival in Paris, his monologue with Haydee in the carriage as he reminisces about his suffering before his deal with Gankutsuou. The scene looks like it came straight out of a gothic horror film, complete with pouring rain and crashing thunder as lightning illuminates his red eye and menacing grin. Haydee is scared because she doesn't know if it's the Count or Gankutsuou talking, and because they both know that the wheels of revenge are now turning at full speed; there's no turning back.
- Haydee's reaction upon seeing Fernand Mondego. As she collapses, it looks like she's about to fall over the railing, but the Count catches her in time. As he carries her out, he looks like a conquerer emerging victorious, and when she wakes up in the carriage, he isn't the least bit concerned about her state; he asks her if she saw "that man", and smiles coldly.
- The scene between the Count and Madame Villefort in her greenhouse. The Count seduces her with his insight about the beauty of death by poisoning, and she gives into his words. The buildup of the poisonous seduction is really disturbing and creepy, especially after the Count gives Madame Villefort a Borgia ring which is rigged with poison, and it looks like they're about to get intimate (with Albert watching them through Maximilian's binoculars). The Count's ghastly grin and sudden widening of one of his eyes when he spots Albert watching makes one worried that he's about to rush at him and rip his throat out.
- Has anyone noticed the freaky painting in the room reached by Albert, Villefort, and Madame Danglars????
- Andrea at one point attacks Haydee with a crazed look on his face and looks like he intended to rape her but the Count shows up and demands that he take his hands off her. Andrea isn't happy about the interruption, and even looks like he wants to challenge him to a fight, but stops when he sees Gankutsuou's eyes glowing on the Count's forehead, a clear indication that he would just get curb stomped and ripped limb from limb. Bonus points to the Count's face being concealed in the darkness once again, so it's hard to see his expression, but one can only guess how pissed off the man really is ...
- At the end of episode 15, the Count sends Albert back to Earth and then he cries, knowing what he had done to Albert. But when they show close-ups of his face, only half of it is sad, the other half is the evil Gankutsuou smile. Now that by itself is creepy, but when the Gankutsuou side takes over, the cries immediately transform into the freakiest evil laugh ever heard. Joji Nakata provides a knock-out performance and the animation supports the moment brilliantly.
- Andrea Cavalcanti at first seems like an effortlessly charming Bishōnen but is eventually revealed to be outright deranged to the point of seducing his mother and almost raping (or does he really?) his half sister and stabbing his father.
- Baron Danglars' Death by Materialism moment, when the Count traps him on a spaceship that is dead in the “water”. At first he reacts appropriately, trying to escape... until he notices the gold bars. He disrobes, embraces the gold, and wastes away making no attempt to save himself. It's hard to tell if the Count's idea or Danglars' reaction is scarier.
- When Vilefort begins to go insane from the toxin Andrea injected him with. We get to see it, from his perspective, as his grip on reality comes totally undone, and the once normal classical music that was playing from his stereo becomes a nightmarish wail. The worst part? The scene cuts off before his descent is complete, leaving the rest to the viewers' imagination.
- The aftermath isn't pretty either. As Fernand enacts his coup and bombards Paris, Villefort is wandering aimlessly through the streets, still acting a Hanging Judge, pointing at people and raving for them to be arrested until one of the bombs seemingly blows him away.
- From what little we see of the Chateau d'If, the punishments are horrific beyond imagination. Our only example, the Count, was used as part of the Wetware CPU for its defense systems. The agony was such he actually would have died purely from the pain alone had the same system not been forcibly keeping him alive. Prisoners were only allowed into their cells to sleep for a bit before being hooked right back up, over and over until they finally expire.
- Everything that involves Gankutsuou, especially the Nightmares people have of him. It’s a being so unfathomably evil that even those in power have uncharacteristically altruistically tried to erase it from existence and history despite the undeniable power it offers.
- The records found by Franz also dub Gankutsuou as the Man in the Iron Mask. We're not given the details, but if you're familiar with Real Life French history and the many theories surrounding that particular myth, you know it must have been really bad. And indeed, in the flashback we get from Dantes' stay in Chateau d'If, Gankutsuou looks like a desiccated, demonic version of the trope.
- The worst part? Aside from how it affects the Count's body and some of the Count's vague feats of either illusionism, teleportation or Healing Factor, we never get any concrete idea of what powers Gankutsuou truly offers.
- The constant pain that the Count is in when he is keeping Gankutsuou at bay. By the penultimate episode, he seems to be aware that the medicine he takes may no longer work, so he refuses to do so, and just lets Gankutsuou take over, and the sight causes Haydee to faint from pure terror.
- From Albert's point of view, the whole series was a never ending nightmare. Your mentor and substitute father stalking you and trying to kill you. Your dad turning out to be a parvenu and an opportunistic betrayer and murderer, then bombarding the entire city as par of a coup before trying to kill you along with your mom, then trying to kill a young girl whose father he already murdered (on top of selling her as a slave). All of this happens in, at best, a few days to a week!
- The chaos in Paris after Albert's father starts a coup. They leave Parliament more or less unharmed but the same cannot be said of the civilians. In addition to the already terrifying-from-a-civilians-perspective Longsword Mecha, other mechanical monstrosities are seen prowling the streets, killing any who resist (and even some who don't)
- As mentioned above, after Franz's death, Albert has a dream that ends in him killing Franz himself. But unlike in real life where he was stabbed in the dream he doesn't just die; his entire body turns in a mass of blood, as does everything around him and Albert, all the while cursing Albert. Talk about a bad dream.
- The end of episode 19 where Andrea assaults Eugenie pinning her to the ground with the intent to rape, ripping her clothes off violently all the while laughing maniacally about how he will "ruin her". It's very distressing to watch. He thankfully reveals next episode to Albert while taunting him that he didn't go all the way, simply blackmailing her into marrying him without running away. Unless he was lying, albeit Eugéne seemed unharmed and non-scarred during the episode.
- Oh, and let's not forget that he had just seduced and slept with her mother prior to that. Or rather, THEIR mother, making her his half-sister too.
- The Count's transformation after kissing Haydee following her Anguished Declaration of Love. There are black holes where his eyes should be, and his fangs are showing. And then Gankutsuou takes over, and SIX EYES APPEAR ON HIS FACE. Small wonder that the sight caused Haydee to faint.
