- Misuzu: "What...are you...!?"
- Ira: "Our mission is to terminate all those who set foot on the ground of this palace!"
- Misuzu: "Terminate...?"
- Acedia: "Killing the six of you... That is our mission."
- - Misuzu exchanging words with the two Black Knights Ira and Acedia during their first encounter.
The Black Knights are 6 mysterious figures who reside and protect the crystal imprisoning Lisette Vertorre within Red Night. They call the protagonists 'Fragments' and try to kill them for unknown reasons. It is later revealed that they are a group of Index's apostles called the Punishment Squad who sealed away a witch called Lieselotte Werckmeister 64 years prior to the events of the story with the price of their own lives, while Lisette is, in fact, an amnesiac Lieselotte. In order to protect the seal from being broken, Superbia, the only survivor used her soul binding art to bind the souls of others into the bodies of the Larvaes inside Red Night after the battle.
In the anime, however, the Black Knights' forms are the result of the spell they used to seal Lieselotte.
- Main article: Avaritia
The leader of the Black Knights and determined to crush the "Fragments". In actual, he is one of the 14 saints from Index, called Georgius of the Rainbow. He was sent out with his subordinates to eliminate Index top priority threat, Lieselotte Werckmeister. After a seemingly losing battle with Lieselotte at Ayame Hill 64 years ago, he used his last resort, the forbidden technique, Contract of the Rainbow to split Lieselotte's soul and the piece of Emerald Tablet within her into seven fragments to weaken her. Lieselotte with one of the fragments remains in her body was sealed within the crystal. The other fragments, due to the technique, was scattered across six parallel worlds. This explain why he calls the gang "Fragments" because their bodies contain those "fragments" and those "fragments" are the sources of their powers. In his past mission, he sealed a dragon within his body with the same technique and release it in the final battle to crush the "Fragments" and Lieselotte with the price of losing himself. It took a lot out of him to maintain seal of the dragon within his body and at the same time Lieselotte's seal.
- Main article: Superbia
The most powerful Black Knight after Avaritia. She fights using two Japanese swords that are similar to Misuzu's. She is in fact the only Black Knight who has no association with Index. Rather, she is actually Misao Kusakabe, the Kusakabe onmyouji that Misuzu admires. She reveals that her two swords were part of Kusakabe's treasures. The swords she has, Onikiri and Kumokiri, in additions to Misuzu's, were once referred as Kusakabe Seven Swords. After she took the two swords and leaves her clan, the swords that Misuzu has then become Kusakabe Five Treasures. In the game, she looks down on all the "Fragments" and Kakeru except Shiori because only Shiori is strong enough to fight her. She is also the only member of the Black Knights who is actually alive or living without burden. The four subordinate's of Georgius are actually dead and their souls are bounded by her with Larvaes(the Red Night's creatures) as their bodies. She also sealed their memories they have while they are alive. She also contribute part of her power help keeping the dragon sealed within Georgius. It is hinted that she helps Georgius and his group because she admires and loves him.
- Main article: Ira
The second Black Knight to be slain. Killed by Kakeru, a slimly muscular male with predatory slanted red eyes and is armed with syths embedded on his fore arms. He is specialized in Chinese martial art. He is actually an apostle of Index and a subordinate of Georgius. His index's name is Sebastianus of the Holy Bone.
- Main article: Invidia
She is the only female Black Knight beside Superbia and is the only member with wings that can fly. She use a sword that resemble a spine that specialize for long range attack. The fourth knight to be killed. She plans to explode herself and take down everyone in Kakeru's gang with her. Her attempt fails due to Yuka's awaken power and Yukiko killed her by stabbing on her forehead. She is also a subordinate of Georgius of the Rainbow and her Index's name is Irene of the Dragon Skeleton. In the game, it is revealed that she loves Sebastianus.
- Main article: Gula
One of the Black Knights, whose figure is a giant fat male with a club as its weapon. It is also the first one to die. Was killed by Misuzu. His role in the story and within the Black Knight group is most minor. His Index's name is Samson of the War Hammer.
- Main article: Acedia
The "mage" of the group, as he is after the bearer of the eye of Aeon. He uses scrolls as his weapon. He is quickly killed by Kukuri, however one part of its head "Scholastica" manages to flee, causing it to survive. However it is killed by Shiori afterward. In the game, his two-parted head is cut down by Misuzu using Doujikiri and Scholastica dies at this time instead and Acedia is killed by Shiori afterward. Scholastica is actually Acedia's sister and they share a body. His Index's name is Benedictus of the Bookshelf. It is reveal by Shiori that Benedictus and Georgius are people in her family line. Shiori refers to him as her prototype when she kills him.
- In the 11eyes OVA, Superbia, Acedia, Invidia, Gula and Ira forms a Power Rangers style group called the Erotica Five. They died in a explosion after their show.
- Their names are taken after the 7 cardinal sins. There is no "lust" amongst their team, but they often call Lieselotte "Luxuria".
- In the anime, the order of their deaths is a bit different from the game. Gula is the first to die, then Ira, Acedia, and finally Invidia. Avaritia is absorbed into the same time-rift as Lieselotte to keep her from escaping. Superbia's fate is left unknown.
- In the anime, except for Avaritia, Superbia and Acedia, the names of the other Blacks Knight are not mentioned.
- There is an official fancomic series has been released altogether with the anime featuring the Black Knights, although a lot goofier than the original, explaining the anime to audience. This fancomic series has been included in the Bluray release.