埃忒耳（Αἰθήρ / Aether，“上空”）在希腊神话中是“太空”的拟人化神，他代表了天堂。他是众神所呼吸的纯洁的天堂空气（一说是天堂的光线），不同于凡人所接触的空气（ἀήρ / aer）。在赫西俄德的《神谱》中他是厄瑞玻斯和倪克斯的儿子，赫墨拉的兄弟。他们在西塞罗的《论神性》（De Natura deorum）也被提及。他是世界的灵魂，所有的生命从他而出。埃忒耳还被作为宙斯的保护墙而为人所知，他将塔耳塔罗斯（地狱）拦在宇宙之外。“以太”之名来源于他。

Aether /ˈiːθər/ or Aither (Æthere, Ancient Greek: Αἰθήρ, pronounced [aitʰɛ̌ːr]), in ancient Greece, was one of the primordial deities. Aether is the personification of the upper air. He embodies the pure upper air that the gods breathe, as opposed to the normal air (ἀήρ, aer) breathed by mortals. Like Tartarus and Erebus, Aether may have had shrines in ancient Greece, but he had no temples and it is unlikely that he had a cult.