- Sayaka Miki (美樹 さやか Miki Sayaka?)
- Voiced by: Eri Kitamura (Japanese), Sarah Williams (English)
- Sayaka is Madoka's classmate and best friend, a second-year at
Madoka's school. She is a lively tomboy with strong ideals of love and lawfulness. After helping Madoka rescue Kyubey, she contracts with him to grant her wish to heal the wounded hand of Kyosuke Kamijo, a young violinist that she is infatuated with, visiting him daily in the hospital. As a magical girl, Sayaka's weapon of choice is a cutlass, being able to produce multiples of them at a time. She also has an extraordinary regenerative ability due to the healing nature of her wish. Sayaka insists that her wish is selfless and feels that fighting witches to save people is a bonus, even after witnessing Mami's death. As Sayaka's ideals are put against the reality of her wish's consequences and the stress of fighting, her view of the world is slowly corrupted. She becomes hateful and distrustful towards others, including Madoka, whom she lashes out at and accuses of being selfish. Because of this, Sayaka seems to be based off the original story of the Little Mermaid, because like the little mermaid who saves the prince from near-death, Sayaka heals Kyousuke; like how the little mermaid gives up her tongue to become a human and get the prince to fall in love and marry her, Sayaka gives up her humanity so she can heal Kyousuke and also get him to fall in love with her; like the prince instead falls in love with another princess and breaks the mermaid's heart, Kyousuke falls in love with Hitomi, breaking Sayaka's heart; Finally, like the little mermaid is told to kill the prince and have his blood drip onto her feet so she can turn back into a mermaid, but doesn't and turns to sea foam, Sayaka refuses to cleanse her tainting Soul Gem, causing her to turn into a witch, who is like a mermaid.
- After learning that her soul is no longer in her body, but in her
soul gem, Sayaka starts to believe she is a zombie; and when her friend Hitomi confesses to her about her love of Kyosuke, Sayaka falls into isolation and refuses all help. In her despair, she loses faith in humanity and justice, making her give up on her ideals and herself; thus leading to her soul gem becoming fully corrupted, turning into a grief seed, making her into the witch known as Oktavia von Seckendorff (オクタヴィア・フォン・ゼッケンドルフ Okutavia Fon Zekkendorufu?), the mermaid witch, an armored mermaid witch with her barrier resembling a concert hall, where a figure similar to Kyosuke is playing among faceless figures. Though Kyoko and Madoka attempt to communicate with her, they realize that they can't do anything to save Sayaka. Kyoko then performs a powerful attack to finish off Oktavia, taking her life along with the witch's.
- Despite Madoka's reworking of the world in the final timeline,
Sayaka still makes a wish in the new world, and thus ends up disappearing after exhausting her soul gem. Despite this, however, Sayaka does not regret her wish, and hopes that Hitomi will make Kyosuke happy, before leaving with Madoka to the afterlife.
- In Rebellion, Sayaka assists Madoka and Nagisa in saving
Homura, and has received knowledge of all previous timelines as a result of becoming a part of the Law of Cycles. She shows the power to summon and manipulate witches, including her own witch form Oktavia, though she can control Oktavia independent of her body, unlike Nagisa. Sayaka states that she became an assistant of Madoka because she "regretted leaving Kyoko behind".
- At the end of Rebellion, Sayaka and Nagisa were pulled from
afterlife by Homura, and given a new life and human forms in the new world. Unlike Madoka and Nagisa, Sayaka retained all her memories in the new world, however Homura took these away too after their confrontation. Even so, Sayaka promises that she will never forget that Homura is a demon.