Ug-Qualtoth

Ug-Qualtoth is a supernatural, eldritch entity. An altar dedicated to the worship of this being resides in the virulent underchambers of the Dunwich Building in 2277.

Background
Anthropologists have speculated the swampfolk have a belief in the occult, and some postulate they pray to an entity named Ug-Qualtoth.

A strange altar found in the depths of the Dunwich Building may hold the key to discovering more about this previously unknown entity. Unfortunately, because all investigators into grimoire oddities are currently attempting to scrape together a day-to-day existence or are dead, further research may never occur.

Legend states that pressing the fabled Krivbeknih into this eldritch obelisk can force those of impure blood to face a fiery death.

Quests

 * The Dark Heart of Blackhall: Destroy the Krivbeknih on this altar instead of giving it to Obadiah.

Appearances

 * An altar of Ug-Qualtoth appears at the Dunwich Building, and is also mentioned in the Dunwich Building terminal entries in Fallout 3.
 * The Dunwich Borers location in Fallout 4 is tied to Ug-Qualtoth worship. When descending the mine, a dream sequence reveals that occult ceremonies occurred there and the ritual weapon Kremvh's Tooth can be found. Clues found inside hint the Dunwich company management knew more about the cult but kept it secret.

Behind the scenes
The altar of Ug-Qualtoth, as well as its placement within the Dunwich Building and significance to the swampfolk is a reference to H. P. Lovecraft's short story, "The Dunwich Horror", in which a swamp-dwelling family breed the offspring of a cosmic entity, Yog-Sothoth, which proceeds to wreak havoc on the neighboring town of Dunwich. The building's name is a direct reference to Lovecraft's short story with Ug-Qualtoth being a similar-sounding replacement name for the cosmic entity it features, and the swampfolk being replacements for the family that also appears in the story.