Greek goddess of the night

NYX

This primordial figure’s name is just three letters and personifies darkness itself.

The clue refers to Nyx, the primordial Greek goddess who personified night in ancient mythology. She was one of the first deities, often depicted as a shadowy figure emerging from chaos at dusk. The answer is simply her name spelled in its most common English form, "NYX," which is short and fits neatly in crossword grids. No wordplay is involved—it’s a direct reference to her well-known role.