He resembles a gigantic, humanoid frog, or a Deep One, with only a single, huge eye in the center of his forehead like a cyclops. A dense mane and a beard of writhing tentacles grows from his head. Although never fully described in Lin Carter's own stories, Ythogtha is incredibly large; when the sorcerer-priest Zanthu attempts to free Ythogtha from his prison, he mistakes his god's clawed, slimy fingertips for mountainous heads.
The Elder Gods imprisoned Ythogtha in the Abyss of Yhe. He is served by the planarian-like yuggs and their lord, Ubb, The Father of Worms. Ythogtha's legend is chronicled in the Zanthu Tablets.