Yog-Sothoth

Yog-Sothoth (nickname: the All-in-One) is a fictional character, an Outer God from H. P. Lovecraft's Cthulhu Mythos.
Yog-Sothoth has several different avatars:

• Aformorgon
• The Dweller on the Threshold
• Tawil-at-U'mr

Quotes

"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

"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 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

Source