is a familiar who can grant any wish to a certain girl, on the condition that she become a Puella Magi and fight against witches.
When someone makes a contract with him, he extracts their soul and places it inside a Soul Gem, replacing their body with a shell that's more resilient to fighting witches. He has so far made contracts with Mami, Kyouko and Sayaka, and shows particular interest in making Madoka a magical girl. It is yet to be revealed if there are other familiars besides him. As a magical creature, he can only be seen or heard by Puella Magis and those with magical potential. He is shown to consume used Grief Seeds, though for what reason is unknown. His true motives are unknown, and he constantly tries to find chances to persuade girls with magical potential to form a contract with him despite knowing the dangers that a Puella Magi faces. He tends to have little understanding of human values and doesn't believe what he's doing is cruel. If he is killed, another Kyuubee takes his place and consumes the previous one. Homura recognizes his true identity as Incubator.
