In the fiction of J. R. R. Tolkien, Eä is the Quenya language name for the universe, as a realization of the vision of the Ainur. The word comes from the Quenya word for to be. Thus, Eä is the World that Is, as distinguished from the World that Is Not. It may thus be assumed that everything outside Eä, including the Timeless Halls of Ilúvatar, has no material form.

The Ainur, angelic beings from the Timeless Halls beyond Eä, refer to it as "the Little Kingdom". This refers to the fact that within the mind of Eru Ilúvatar (God, in Tolkien's legendarium), all creation that human can see is really just a tiny thing in comparison.

Eä was the word spoken by Eru Ilúvatar by which he brought the universe into actuality. This act of creation recalls the Biblical creation narrative, in which God began creating the world with the verbal command, "Let there be light."