Melkor, also known as Morgoth, was the wicked Vala brought forth by Eru to add discord to the music, making it more beautiful. He strove eternally to work against the music, but this was the purpose for which he was created.

The Free Imperia religious scholars find many parallels between Morgoth and Old Ones mentioned in the lore of other spheres.

He is prophesied to return at Dagor Dagorath.

Daur-Phazan Landosalan is a Black Númenórean Priestess of Morgoth.

M'rgot Adl'r is a Black Númenórean Priestess of Morgoth.

Outside sources:

Tolkien Gateway on Morgoth