Gyuuki

Gyuuki, also known as Ushi-Oni (牛鬼, lit. Ox Demon), is a bovine-like youkai who dwells in the sea. While most notably appearing as an antagonist, in some adaptations he is depicted as an ally of Kitarou.

Gyuuki is a Kaijuu with the head and horns of a cow but the body of a spider. His face is demonic-looking, with a wide smile and sharp teeth.

In general, Shigeru Mizuki's depictions of Gyuuki share many similarities with that of Tsuchi-Gumo.

(Source: GeGeGe no Kitarou Wiki)