阿修羅, Kishin
The strongest and most dangerous primary antagonist in Soul Eater and the first demon god. He was supposedly a human however he was an embodiment of Fear and Terror who existed before Shibusen with strange habits: he would cover his head with long scarves and he wore five to six shirts on his body this was because he did not trust anyone and because of that the Shinigami said he had a careful soul. He was the strongest member of the Eight Powerful Warriors Shinigami a group made up of The Shinigami Asura Eibon and five other still unnamed members. He was powerful enough that he destroyed all the witches of the East by himself. The Shinigami explained that he was always terrified by the greatest fear possible so to protect himself Asura became attached to power and started taking souls of people who were not listed he even went as far as to eat his own partner out of fear this caused him to go mad and become the first kishin. To stop him the Shinigami removed all of Asuras skin and used it as a seal on Asura to trap him under the school then the Shinigami rooted himself to the very ground of Death City and uses his soul and body to prevent Asura from awakening. He is eventually awakened in volume six of the manga by Eruka and Free. He managed to knock out Black Star and Kid in one blow and fight The Shinigami on equal ground. After fighting The Shinigami he flew to an unknown destination. Although he ate his own weapon partner whose weapon form is a vajra Asura can cough up the his weapon for use in combat. Even though he was sealed up and killed by Shinigami they seem to be able to speak in an almost friendly tone when they met again Shinigami wondering whether Asura felt nervous without his layers of clothes and Asura wondering about Shinigamis new mask. Source: Wikipedia