The Espers in this game look either grotesque or uncanny, especially compared to those of previous games. Specifically:
If read the lore in the Bestiary, you know that the woman attached to Zalera was some sort of shamaness that the esper fused to himself and is now using as some sort of grotesque puppet. The chilling scream that rings out during the animation for Condemnation is the aural manifestation of her never-ending torment at the hands of her master. Happy nightmares.
It's worse when you face Zalera as a boss; his super move is Prime Lv. Death, which instantly kills all active party members whose levels are prime numbers note 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, and 97. Here's the kicker: the animation is Zodiark's Darkja with the woman's skull coming at you. (Here's a link for it If you dare◊ )
Cuchulain's Blight, what with him jumping up in the air, jiggling around his fat only to have a scorpion tail burst out of his back, strike the ground and poison the surrounding environment. His monstrous appearance, which is the result of swallowing the world's corruption, doesn't help matters.
Mateus's appearance is more than unsettling after you read the Bestiary. The woman you see is an Ice Goddess he bound to his torso to attempt and overthrow the Occuria. He never let her go.
Zodiark is in a way very disturbing - basically, he's a small, immature snake-like being with the power to destroy the universe on a whim. And you have to go up to it and stab it to recruit it. Made so much worse in that the freaking Occuria are scared of what he might do when he reaches adulthood.
You can see said adulthood on his Limit Break, Final Eclipse. Just watch it, and see why Zodiark is so feared.
Since the world is now free from the Occuria, Zodiark now sports a pair of huge angel wings like he did when he used Final Eclipse. That's right folks, the all-powerful infant is growing into an Up to ElevenEldritch Abomination
Looking at the backstory makes many of the random monsters unsettling. Reading the bestiary is an exercise in stealth nightmare fuel - nearly every monster, summon, or bit of random Vendor Trash has some horrifying story attached to it. The specific ones mentioned are just some of the most gruesome. For example, all dark humanoid monsters like ghosts, skeletons, or headless were once men who, after dying, are put in some sort of half-living state where they are to suffer for nigh all eternity, with the slaughter of others being their only reprieve.
There was one creature called Necrophobe or something that was so afraid of dying it instinctively kills the hell out of everything.
"Being a particularly accursed variety of ghost, that fearing death so greatly, wanders in denial of his own demise. So irrational is his fear, he is certain that all who cross his path mean him mortal harm, and so strikes first. It is recorded in the annals that once, when a score of these cruelly afflicted beings appeared in a village, they were halted by magickal panels facing each of the cardinal directions, this device barring all misfortune from entering the homes of the people who lived there. Safe though they were, the villagers were nonetheless besieged. Fearing starvation as much as the violence of their enemy, many contemplated suicide, but as the sun set on the third day, they peered through their windows to find that the ghosts had vanished, never to be seen again."
Nabudis, or what's left of it anyway. There is a reason why its called The "Necrohol", and its hard to imagine that anybody once lived there. The creepy music, along with the swirling mist and the fact that monsters can jump at you at any moment really drives the point home.
The creepy, spidery way Fran's sister Mjrn limps and runs when possessed is certainly this. That was in no way normal.
Vayne Novus. He falls RIGHT into Nightmare Face with his distorted features.
Barheim Passage at first seems like just another crawl through tunnels, but then, spider-like monsters known as Battery Mimics begin consuming the electricity in the tunnels. If they manage to devour all the electricity, the lights are killed, and sensing the darkness, the undead emerge from dormancy to prey upon the party.
If that wasn't enough, there are Mimics that disguise themselves as treasure, and players who blindly open treasure chests will find themselves ambushed by a creature whose first action is to suck the blood of its victim.
You'd think the weaker (read: mandatory) wall would be less creepy than it's optional counterpart. NOPE. It's harder to get a "crushed to death" game over on it because the battleground is longer and you can stop it temporarily (or speed it up if you're not good picking out the braziers along the floor), but at least the stronger wall doesn't end it's instant game over cutscene by focusing on the wall's face (complete with eyes flaring!) before abruptly cutting to black to give you the game over screen. GAH. The optional demon wall's scene ends with the player actually seeing it smash into the wall, not just end on an evil face shot.