Aether or Aither, was the protogenoi of the upper air. He was the consort of Hemera, who was also his sister. He was a son of Nyx and Erebus.
In Popular Culture
The Aether appears in Thor: The Dark World. In the film, instead of been an entity or god, the Aether is a primordial element or substance whose existence preceded that of the Nine Realms. The substance is red and black, and although it is an Infinity Stone on the film's story, it is the only stone appearing in liquid state.
In ancient and medieval science, Aether (or ether) was the name of a mysterious fifth element, the definitions of which vary.