Zom is an incredibly powerful monster from Marvel comics and an enemy of Doctor Strange, Zom is said to be powerful enough to dwarf Doctor Strange and beings such as Umar or Dormammu with ease - however he is nowhere near as powerful as an omnipotent being such as the Living Tribunal.
Zom claims to have been created to destroy, but his creator and the methods of his creation are unknown. Ages ago, he was defeated under unknown circumstances, which may have involved a union of several other extremely powerful beings, including Dormammu (the ruler of the Dark Dimension) and Eternity (the cosmic being representing the entire temporal axis of the Earth dimension). To protect the universe from his might, Zom's hands were bound with Chains of Living Bondage by Dormammu. Zom was forced to wear a Crown of Blindness, and his essence was imprisoned by Eternity within an Amphora in a "world beyond all worlds" in a "time beyond all time."
However many years later Zom would be released and come to blows with Doctor Strange on several occassions - each time being reimprisoned.
Zom's most recent return was in World War Hulk when a desperate Doctor Strange utilized Zom's power to take on the Hulk but became overwhelmed by the bloodthirsty demon and had to work together with several other heroes to stop Zom from worsening the situation.