|Drops||Silver Demon's Soul|
|Stats are sourced from Atlus's Official Demon's Souls Guide|
A tall, knight-like Demon, the Penetrator wields a long Penetrating Sword that glows with a blue light during every blow. It can perform a devastating thrust attack, but it's rather slow as the rest of his offensive maneuvers. His sword can destroy the pillars in the room.
If the player freed Biorr in the previous level, then he will join the fight as soon as it begins. He will ask if the player needs any help and continues to distract the Penetrator with his great sword. Although his attacks do deal a large amount of damage, he barely uses, if ever, his greatshield. He will wield his crossbow in his off-hand, allowing for damage if the Penetrator decides to focus on the player. Biorr may die if Penetrator is not killed quickly enough, especially on NG+ or higher.
With or without Biorr, the Penetrator boss fight can be a difficult boss without properly timed dodging. As indicated by the sword's blue glow, Penetrator's attacks deal magic damage as well as regular physical damage. When he pulls his sword back and it starts to violently glow blue, however, he will proceed to impale the player on his sword and deal a very large amount of damage. This attack can be evaded by rolling to the side, but rolling into the attack sometimes works. Most of his other attacks consist of circular slashes and lunging cuts.
The Penetrator's attacks destroy the surrounding statues on contact. However, they do block his running and walking, allowing the player to heal or maneuver. This boss is particularly vulnerable to magic and blunt damage.
- The Penetrator's sword can be found earlier in 1-3, although it doesn't glow or deal magic damage.
- Ostrava implies that the Penetrator was once Metas, Knight of the Lance, one of King Allant XII's circle of elite knights.
- Penetrator shares his boss theme with the Tower Knight.