In Assassins Creed Odyssey, the main antagonist is a group called the Cult of Kosmos. Was there a deity in Greek mythology named Kosmos?
For Egyptian, you'd have several choices. Going from the largest (at least in the Heliopolitian cosmology):
Nuun (Nun) is the cosmic ocean that our universe is a bubble in: https://henadology.wordpress.com/theology/netjeru/nun/
Atum includes the concept of "Completeness". In a sense He/She would be related to the universe we know, and precipitated himself/herself out of the Nuun.
Shu and Tefnut would be next- Shu having a complex set of associations including emptiness and light, and Tefnut with moisture (and another set of associations).
From those two came Geb- associated with Earth, and Nut with sky. The Nuun also passed underneath the Earth.
The above is a gross simplification, especially when you mix in all the other Egyptian creation stories.
Several of the Greek philosophers talked about a spherical Earth: they noticed that you could see stars in the Southern Egyptian sky that were invisible in Greece, the reverse being true for Northern stars in Greece.
This depends entirely on your stance of if you're asking for a sky god or if you'd prefer only "outer space", so to speak. Given that these are ancient cultures / mythologies we're discussing, it stands to point that perhaps they would have seen the two as synonymous, which was why historically the sky gods were said to be most powerful. For instance, some accounts that I've read in the past read that Zeus became King of the Gods only after he had drawn the lot for the sky, as opposed to either of his brothers (this can also be contested that he became King due to the fact that he was the one who overthrew his father and had to rescue his siblings, which is the most widely accepted version I've ever come across).
Going back the furthest you can in Greek mythology:
There will be Chaos, which was accepted as the "oblivion" or the unknown, and the first being to give birth to all others.
Some accounts tell of the Titan Queen Eurynome (commonly mistaken with Zeus' third bride, and some accounts have them as one and the same person who was an Oceanid).
And of course there is also Ouranos, who is well known as the father of Kronos and the rest of the Titans, and he was depicted as the night sky that hung over the earth, the lover and husband of Gaia.