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-termious 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 billion realities and universe, which means he has abstract appearance. Some of the pictures he look like a fusion of many universe and a taller height, some of the picture, he look like an abstract force, and some of the picture he look like fusion of countless universe and realities. The avatar itself look like a flying thing with many tentacle.

History
Yog-Sothoth is one of the main outer gods. He is the chief in command after Azathoth himself, the ruler of the Outer Gods. But with his power he can destroy many universe, dimension, and realities without his full power. This is make him the strongest of the outer gods. His avatar and many other outer gods living in the court of Azathoth, the center of all infinity. He is by far known to be the only alien gods had a counterpart of the human, he has a son. His son is name Wilbur Whateley with unknown mother.

Trivia
Yog-Sothoth is the largest alien in alien species wiki, being size of billion realities because he is the Multiverse itself. The second largest being is the Extra-Galactic Alien.