Thetis is a Greek mythological figure and a sea nymph, and a minor goddess of water. In the SpongeBob world, she is a demiurge-like figure within the watery territories of the God Homeworld of Mount Olympus, being one of the 50 Nereids, whom used to be deviant evil Amazon-like jerks who were exiled by King Neptune I for crimes against mortals, and Thetis was left behind for betraying them to Neptune. She has since become an enlightened demiurge who seeks what is best for the gods of the sea, while her sisters would later join Triton in his new evil quarter-life crisis quest of who he wishes to be, being lead by The Tritones, while Triton would also get his ancestor Oceanus, and his pet Cetus, while he himself would be used by SpongeBob's variant of Hades as a way to use his evil father Kronos against his other brothers, Poseidon (King Neptune) and Zeus, as well as SpongeBob's counterpart of Hercules, only this time in a traditional means as 12 Labors. Thetis has the ability to bless godly powers for the protection of those whom she casts among, granting them the impossible ability to be equal in power against a god like Triton.
Thetis is a mermaid goddess with long elegant glowing white hair, and an elegant white and blue dress, carries a powerful trident like Neptune's, has seashell bikini plates, green-blue skin, beautiful cyan eyes, and golden armlets and headband.