Yog-Sothoth

Yog-Sothoth (The Lurker at the Threshold, The Key and the Gate, The Beyond One, Opener of the Way, The All-in-One and the One-in-All) is a cosmic entity of unknown origin. Yog-Sothoth is co-terminous with all time and space and he is one of the Outer Gods.

Quotes
"Imagination called up the shocking form of fabulous Yog-Sothoth — only a congeries of iridescent globes, yet stupendous in its malign suggestiveness."

- H.P. Lovecraft, "The Horror in the Museum"

"It was an All-in-One and One-in-All of limitless being and self — not merely a thing of one Space-Time continuum, but allied to the ultimate animating essence of existence's whole unbounded sweep — the last, utter sweep which has no confines and which outreaches fancy and mathematics alike. It was perhaps that which certain secret cults of earth have whispered of as YOG-SOTHOTH, and which has been a deity under other names; that which the crustaceans of Yuggoth worship as the Beyond-One, and which the vaporous brains of the spiral nebulae know by an untranslatable Sign..."

- H.P. Lovecraft, "Through the Gates of the Silver Key"

"Yog-Sothoth knows the gate. Yog-Sothoth is the gate. Yog-Sothoth is the key and guardian of the gate. Past, present, future, all are one in Yog-Sothoth. He knows where the Old Ones broke through of old, and where They shall break through again. He knows where They have trod earth's fields, and where They still tread them, and why no one can behold Them as They tread."

- H.P. Lovecraft, "The Dunwich Horror"

"...great globes of light massing toward the opening, and not alone these, but the breaking apart of the nearest globes, and the protoplasmic flesh that flowed blackly outward to join together and form that eldritch, hideous horror from outer space, that spawn of the blankness of primal time, that tentacled amorphous monster which was the lurker at the threshold, whose mask was as a congeries of iridescent globes, the noxious Yog-Sothoth, who froths as primal slime in nuclear chaos beyond the nethermost outposts of space and time!"

- H.P. Lovecraft, "The Lurker at the Threshold"

Physical Appearance
Yog-Sothoth is made of (and simultaneously exists outside) innumerable realities and universes, which means he has an abstract appearance that is impossible to visually show. Artists have attempted stylised impressions- in some pictures he resembles like a fusion of many universes, and in others, he appears as an abstract force, and some illustrations his image can be described as a rendition of the fusion of countless universe and realities. The avatar of Yog-Sothoth itself looks like a flying, shapeless form with many tentacles and protuberances.

History
Yog-Sothoth is the second greatest of the Outer Gods, after Azathoth. The power of any Outer God is incomprehensible and unquantifiable, and he is omnipotent, omniscient, and omnipresent. His avatar and many other Outer Gods reside in the court of Azathoth, at the 'centre of infinity'.

Many magical incantations invoke the power of Yog-Sothoth. One resulted in the impregnation of a woman by Yog-Sothoth, yielding the outwardly human Wilbur Whateley and the 'Dunwich Horror'.

Trivia

 * Yog-Sothoth is the largest alien on the Alien Species Wiki, being larger than can possibly be comprehended, because he is (and is also outside) the Multiverse itself. The second largest being to date is the Extra-Galactic Alien.