Abyss Feeder

Abyss Feeders (深淵喰い, Shin'en Gui, literally Abyss Eaters) are a new kind of experiment created by The Organization. Their main purpose is to hunt down and kill Isley, the Abyssal One of the North. There are eleven of them in total.

History
The Abyss Feeders were created seven years previous to the current timeline from the 11 Awakened Beings of Isley's army who went to the east of the island after the destruction of Pieta. Instead of normal Yoma flesh being used, which creates regular Claymores, flesh of Awakened Beings that had been killed by Alicia and Beth was used. The result was creatures that had no trace of humanity left, only a craving for blood and meat. The Organization destroyed their eyes, bound their mouths and removed all sense of self, forcing them to crave only a single type of meat, which is Isley's. They were modified to release no Yoki, but that meant they couldn't sense it either.

Dietrich mentions that the current eleven aren't the original eleven. Each time around half die the Organization calls them back and replaces the deceased creatures. Each time an Abyss Feeder dies they transfer their experience to the one going to replace it, meaning they have been slowly been building up the combat knowledge to defeat Isley.

Hunt for Isley
The Abyss Feeders spent their first few years of life hunting Isley, destroying all the villages in the South during their search. They became known to the Claymores as the 'Demons'. They eventually reached a town where they could sense Isley, passing by a terrified Dietrich on the way. They interrupted the battle between Isley and Helen and Deneve. One easily sliced off Helen's right arm and seriously damaged her left eye. Thanks to an intervention by Dietrich the three manage to get away, leaving Isley to the Abyssal Feeders. They force Isley into his Awakened Form. He manages to slice a few in half but, thanks to high speed regeneration, they continue to fight on. It becomes apparent that the only way to kill them is by hitting their heads, which they keep low and out of the way during battle. They begin to overwhelm Isley, even managing to slice off his left arm. Isley manages to slice many in half, but he mentions how it is much harder to hit their heads than it used to be. He brings out his sword but they continue to attack him, preventing him from regenerating. They manage to eat three of his legs, causing him to topple over. They close in and begin to eat him alive.

Attack on Riful
Another batch of Abyssal Feeders lead Alicia and Beth to the location of Riful. They begin an assault on both Riful and Dauf, managing to cause some serious wounds, including ripping off a part of Riful's head. They attack Riful and Dauf again after the attack from the combined Luciela and Rafaela Awakened Being. Riful kills some but is too injured to kill them all. They are then sliced through by Alicia, who is beginning to lose her mind due to Beth's injury.

After Riful is killed by Priscilla, the Abyssal Feeders lose track of their target, instead gnawing aimlessly at a piece of her clothes. They are discovered in this state by Dietrich, who uses this piece to make them follow her to where the Luciela-Rafaela spawn are attacking Yuma. She then sicks the Feeders onto the yoma spike creatures, saving the other Claymore. It is revealed that Abyss Feeders are immune to yoma spike parasites (presumably because the feeders have no sense of self that can be taken over) but being infected instead makes them identify the yoma spike creatures as their targets.