M

M is a killer who goes on a rampage in Ikebukuro one day, causing the deaths of 10 people before he is arrested. He is dubbed "M" by a fansite and has a mysterious interest in Madoka. [Spoiler] The source of his powers is unknown, but thought to have been developed through researching various esoterical philosophies from all over the world. He is capable of "bilocation", a technique where he can multiply himself and teleport the doubles to other places. He has been impossible to identify, having burned off his face and removed all his teeth. [/Spoiler] [Spoiler] He considers Madoka a kindred spirit, and the one to kill him. [/Spoiler]