Tomoe, Mami

Mami is a veteran magical girl and a third-year student at Madoka's school. She lives alone in a penthouse after the death of her parents in a car accident, one which she was able to survive only due to contracting with Kyubey to save her own life.

Mami is particularly focused on saving those around her, with a traditionally selfless perspective on the role of magical girl, and has a habit of giving names to her finishing attacks. Though her outward disposition is cheery and confident, Mami feels deeply alone as she has no friends to confide in or support her as she fights. Due to her desire to save as many people as she can, Mami tends to clash with other Puella Magi who would rather wait for witches to "mature" in order to obtain Grief Seeds, despite that resulting in human casualties.

In the anime:

Madoka offers to become her partner and save her from her loneliness, but Mami is killed immediately after during battle with a witch; as per Madoka's wish, at the close of the final timeline, this witch never existed, and Mami is therefore seen, alive, with Kyoko and Homura at the end of the series. According to Kyubey, she never knew the darker truths concerning Soul Gems and origins of witches. In a previous timeline, learning of these truths drove Mami insane and she attempted to murder the remaining magical girls to prevent them from becoming witches.

In the Oriko Magica timeline:

Mami contemplates letting herself be killed and/or committing suicide so she doesn't become a witch herself.

In The Different Story manga:

Mami's relationship with Kyouko is greatly expanded on, detailing their past as mentor and apprentice who fought witches together in Mitakihara. It is shown that Mami's greatest fear is being left alone and that her deepest regret is using her wish to save herself instead of saving her family. After Sayaka becomes a witch, Mami plans to die together with her.

In the Homura's Revenge manga:

Despite Homura and Madoka's best efforts to change the course of the events, Mami still dies at the hands of Charlotte, except this time she is distracted by Homura.