Little is known of the sea-god Basatan. He has been variously described as a colossal crustacean, a crab-like humanoid and an eldritch abomination covered in fins and tentacles, but which is true - or whether he is able to switch between these forms - is unclear. It is said to be possessed of a green-jewelled ring with magical properties and has an unspecified association with the stellar constellation of Cancer. Basatan is also stated to be less powerful than the other Great Old Ones, but is still worshiped as a deity by many.
- Basatan made its only appearance in The Master of the Crabs (1948) by Clark Ashton Smith.