The Monolith is a giant monster from Marvel comics and enemy of the Avengers.
In an undisclosed past time period ("from time beyond memory"), the entity described only as the Monolith walked through the corridors of outer space. Although it is described on several occasions as being of occult origin, nothing further of its past or goals was revealed. It apparently arrived on Earth at least millennia ago and, after presumably causing mass destruction, was immobilized the sorcerers of the island of Muara in the south seas. The sorcerers buried the body of the Monolith, leaving only the crown of its head exposed, and bound the spell of immobilization into a circular disk. They placed this disk within an alter on the Monolith's crown and dubbed it He Who Protects."
Although the sorcerers are now almost certainly long dead, the Monolith remained entombed below the surface of Muara by the totem until modern times. "He Who Protects" was either sold to or stolen by unnamed parties, who brought it to New York as part of an exhibit at the Museum of Natural History. Two residents of Muara, Bloodhawk and his Teacher, traveled to New York and after an initial conflict, succeeded in convincing the Avengers to return with them to Muara to replace the totem.
Unfortunately for them, they arrived too late, and the Monolith awakened, forcing itself to the surface and beginning a rampage on Muara. No force mustered by the Avengers could begin to stop the Monolith. Bloodhawk suffered one of his bouts of insanity and fled with the totem, but the Beast recovered it and, with aid from Thor, succeeded in replacing it in the Monolith's altar. The Monolith was instantly rendered inert once again, and Thor used his hammer Mjolnir to open a portal to some unnamed dimension to which he sent the Monolith.