Ома

The last and most muscular ghost to be presented, Lord Ohma is a very powerful evil deity capable of controlling other ghosts even if they are sealed away. He holds a hateful grudge against Kayako Miyanoshita. The first thing he did after he was freed of his magical sleep was go after Satsuki and Keiichirou. The only way to seal him away is to imprison him in a huge bell, once the exorcist has enough spiritual power. Satsuki and the gang decide to use the old school's bell, but since Satuski has not developed her spiritual powers at that time, Amanojaku left Kaya's body to fight with Lord Ohma while Satsuki gathered power.

In the end, Satsuki sealed both Lord Ohma and Amanojaku, who was accidentally sealed by Satsuki (the latter sacrificed himself in order for Satsuki to gather enough power to destroy Lord Ohma forever). (Source: Wikipedia)