Eru Ilúvatar, "The One," is the creator of Eä (existence) and the world of Arda, in which the lands of Middle-earth exist. His names are many but he is analogous to the deity known to faiths in later ages simply as God.
In addition to creating the world, Ilúvatar created the angelic beings known as the Ainur who were to be his servants and the guardians of his creation. He also created the races of Elves and Men, who are subsequently known as the Children of Ilúvatar. Eru Ilúvatar is a mostly unseen and unknowable force to those in Middle-earth but he has interceded in mortal affairs on rare occasions. Among them are the removal of Valinor from the circles of the world and the sinking of the island of Númenor.
The Elves are aware of Eru as their creator, though in the Third Age, Men remain largely ignorant of him, viewing the Valar as their gods. Some Men, such as the Dúnedain retain some knowledge of the One through the lore of Númenor. Elves do not worship as such but respect Eru Ilúvatar as well as the Valar and Maiar that serve him.
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