- Ikki is already the bringer of Mind Rape and horribly bloody fights, but he actually tops himself in one memorable fight against Capella, a Silver Saint who threatened Seiya and Saori. Capella's Weapon of Choice is a part of shields attatched to his armor, which can be also thrown as projectiles - so far so good, huh? Well, Ikki uses his powers to trick the guy into believing he cut off his own hands with said disks/shields (no Gory Discretion Shot here), and goes further when the guy ends up Hoist by His Own Petard by having said shields fatally injure him in the chest and stomach before he is shown unharmed but with his mind broken and falls off the cliff they're fighting in.
- The manga rendition of his attack against Wolf Nachi in his first appearance is even worse. In the anime, his illusion punches shatter Nachi's cloth. In the manga? They shatter his body, ripping off his arms when he tries to defend himself and eventually blowing open his torso, spilling his guts and leaving only the spine. Ick.
- Anything that Cancer Deathmask ever does until his Heel–Face Turn in the Hades Saga and the Soul of Gold series. Specially the little matter of these "masks" in the Cancer Temple. And how he can summon a really scary Uncanny Valley as a fighting field.
- In Episode G, the masks scare the crap out of a giant. The giant was effectively a low-powered god who believed himself invincible. That is how nightmarish Deathmask is.
- In the Hades Saga, Sphinx Pharaoh is a Specter from Egypt. He can perform the infamous Test of Osiris to see if you're a pure-hearted person by literally putting your heart in a scale. While you're still alive.
- The series has some really scary music that sets the mood very well:
Nightmare Fuel / Saint Seiya
With all the High-Pressure Blood and the Cruel and Unusual Deaths, Saint Seiya is chock full of this. Kurumada and Co. can come up with such things...