Character: Kaname Madoka 9395h

A 14-year-old girl whose life changes when she encounters the Puella Magi Homura and the familiar Kyubey, who offers to transform her into a Puella Magi herself. She sees herself as a person without special qualities or talents, and after seeing Mami fighting against witches, wants to help people as a Puella Magi the same way Mami does. Madoka becomes uncertain about becoming a Puella Magi after Mami's death in battle, though she still accompanies her friend, Sayaka, on witch hunts. She is averse to fighting and wishes that everyone would get along. She is implied to have large amount of magical potential within her, and Kyubey is particularly interested in forming a contract with her; however, she has yet to take him up on the offer.

Kriemhild Gretchen is the witch form of Kaname Madoka. She appears in the fourth timeline of Episode 10 as a mountain-sized creature. Her name was not shown during initial broadcast, but was added in a Nicovideo broadcast version one week later.

Nothing is known about the specifics of her powers or personality, but her formation in the second timeline involves thunderclouds coalescing into a giant humanoid (the name is not shown then, however, and thus it is not known whether that witch is also called Kriemhild Gretchen). According to Kyuubey, her strength in the fourth timeline is of such a magnitude that she could obliterate the planet within ten days.

Source: Puella Magi Wiki