- Crona (クロナKurona?)
- Voiced by: Maaya Sakamoto (Japanese), Maxey Whitehead (English)
- Medusa's child and the Demon Swordmaster, serving as the meister of the Demon Sword Ragnarok. Crona's sex is left ambiguous, giving Crona several androgynous qualities, although Crona is seen wearing a skirt during Crona's childhood flashbacks. In the Yen Press translation of the manga and the Funimation dub of the anime, Crona is referred to as a "he" to simplify the matter. Crona is extremely reclusive, expressing uncertainty at interacting with others and dealing with certain situations. At an early age, Crona's blood was replaced with black blood from Ragnarok by Medusa as part of her experiments to create a kishin. This blood can harden to protect Crona from damage and be used as additional projectile weapons through external wounds, though it causes Crona to go insane for brief periods. Crona's childhood was spent by killing small animals and being locked in a dark room for days on end as punishment for disobedience. Unlike normal meister and weapon pairs, who can perform "Soul Resonances", Crona can perform a "Scream Resonance" (悲鳴共鳴Himei Kyōmei?) with Ragnarok to perform various shockwave-based energy attacks. Crona uses Ragnarok to devour innocent human souls until being purified and befriended by Maka. Following Medusa's defeat, Crona becomes a trial student at the DWMA, but is approached by Medusa once she resurfaces and forced to act as her spy within the DWMA. In the manga, Crona is kidnapped by Medusa and brainwashed into forgetting Maka and the DWMA, once again becoming Medusa's test subject for the black blood. As of chapters 87 and 88, Crona has killed Medusa and has been ordered for execution for destroying an entire city and killing a Death Scythe. In the anime, Crona repents for betraying the DWMA by assisting Maka to defeat Medusa once and for all.