Gods from Created Mythos

What are some gods that exist in created myths but don't have actual followers, like the gods created by HP Lovecraft, Lord Dunsany, Olaf Stapledon (he had the Prime Mover in Last and the First Men), William Shakespeare (Setebos from The Tempest), Edgar Rice Burroughs (the Gods in Mars and Tarzan), Robert E Howard's Gods in Conan, or even demons like Mephistophelese and Dante Alegheri's Malbranche. Even invested deities like Caissa (the Greek god of chess who has sno say in the original canon), or Euphron (the invented god of sports).

Note that they should be in the public domain.