The Unnamed Lake Dwelling Demon was a minor character in the first Devilman OVA. Most notably, it is the first demon seen in the OVA.
The demon resembled something of a cross between a tadpole and a plesiosaurus. He had a fat legless body with dark markings and several layers of fins going down his spine. He had large lips and six eyes at the end of stalks.
The demon was the first to attack the Angels as the descended down upon the Earth, rearing up his head and plucking one of them out of the sky, biting the Angel in half.