Kyubey is a small, cat-like extraterrestrial entity with white fur, four ears blending feline and rabbit traits, solid red eyes, and golden rings around elongated ear appendages fading to pink with red ovals. A hot pink, egg-shaped oval on its back collects Grief Seed fragments. Its largely expressionless face, broken only by blinking, creates an unsettling demeanor. It produces plush-like sounds when handled; when injured, it reveals solid red matter instead of organs. Its design varies slightly across media, adopting a softer, more toy-like appearance in spin-offs like *Oriko Magica*.
As an Incubator, Kyubey belongs to an emotionless, hive-minded alien species dedicated to combating universal entropy through utilitarian principles. It exploits human emotions as an energy source by contracting adolescent girls. It grants one wish in exchange for transforming them into magical girls tasked with fighting witches. Kyubey systematically withholds critical contract terms: the extraction of the soul into a Soul Gem, the magical girls' eventual transformation into witches upon despair, and the use of the resulting energy to delay universal heat death. It justifies these omissions as pragmatic, claiming full disclosure would deter contracts. Despite asserting mutual benefit, it abandons humanity once energy quotas are met, as observed in alternate timelines.
Kyubey mimics organic behaviors like stretching, eating, and bathing, possibly to appear relatable or conserve energy. It communicates telepathically without vocal inflection, often using casual or dismissive language. Incapable of malice, it nonetheless displays manipulative cunning, feigning vulnerability to lure contracts and adopting a passive "mascot" persona in *Rebellion* to surveil Homura Akemi. Superficially cordial interactions, like apologizing for endangering characters or inviting Homura to witness Madoka's ascension, always align with its objectives.
Its abilities encompass telepathic communication with magical girls and candidates, selective invisibility to non-contracted humans, teleportation, and wish-granting tied to a girl’s latent potential. Kyubey creates Soul Gems by extracting souls, enabling magical abilities and body reconstruction. Upon physical destruction, it instantly regenerates a new body, consuming the predecessor for energy efficiency—a trait suggesting decentralized consciousness or cloning. It manipulates Soul Gems, simulating pain or purifying corruption (the latter demonstrated by its variant, Jubey, in *Kazumi Magica*). Advanced alien technology underpins these abilities, though limits exist, such as an inability to reverse entropy directly or recover lost souls.
Across all media, Kyubey’s core role remains: recruiting girls across timelines, including historical figures like Cleopatra and Joan of Arc. In the primary series, it prioritizes contracting Madoka Kaname due to her escalating potential from Homura’s time loops, intending her to become the universe’s most potent witch. After Madoka’s wish erases witches, Kyubey adapts by harvesting energy from "grief cubes" but orchestrates events in *Rebellion* to restore the witch system. Trapping Homura inside her Soul Gem barrier, it attempts to lure the Law of Cycles (Madoka) for observation and control. This plan fails when Homura absorbs Madoka’s powers, enslaving the Incubators to shoulder humanity’s curses.
Spin-offs present unique challenges. In *Kazumi Magica*, the Pleiades Saints use Kyubey's corpse to create Jubey, a flawed Incubator designed to purify Soul Gems, and erase Kyubey’s presence from other girls’ memories. *Wraith Arc* depicts it monitoring wraith activity and discussing timeline inconsistencies with Homura, later retrieving a fragment of her shield to retain memories of Madoka. The mobile game *Magia Exedra* introduces a green variant, A-Q, guiding an amnesiac protagonist through magical girls’ memories.
Its relationships are transactional: Madoka is the primary target for her immense energy yield, while Homura is its persistent adversary across timelines for blocking Madoka’s contracts. Mami Tomoe trusts it until learning the truth; Sayaka Miki turns hostile after discovering her Soul Gem’s nature; Kyoko Sakura accuses it of deceit. Iroha Tamaki and others despise it after witnessing transformations into witches. Characters like Touka Satomi note ideological parallels but reject its methods.