Sid is a character from Soul Eater and one of the teachers at the DWMA. Professor Stein turned him into a Zombie.
After being transformed into a zombie, Black Star and his weapon, Tsubaki, and Maka with her weapon, Soul, went after Sid. They defeated Sid in battle and chained him up. The Miesters then went after Professor Stein to defeat him and brought Sid with them.