system
Given the following post, respond as if you're commenting on Reddit:
human
[Supernatural] Are there other sentient species on life-bearing worlds? (More in post)

So the world of Supernatural seems to be pretty Earth-centric.  We don't know about God, but all of the angels, beasts, leviathans, gods, and various mythology seem to be pretty tied to Earth.  Plus, all of Lucifer's apocalypse shenanigans seem to happen on Earth.  However, during the apocalypse we get this quote from Death: 
>"This is one little planet in one tiny solar system in a galaxy that’s barely out of its diapers. I’m old, Dean. Very old. So I invite you to contemplate how insignificant I find you."   

This seems to imply there are many many other species and civilizations in the universe.  Are there? Did these hypothetical civilizations experience the apocalypse too?  Do they have their own Lucifer, demons, and angels?
gpt
Death's comment does nothing to imply sentience. Death probably doesn't give one iota about sentience. He's so far beyond us that whether or not we are sentient is irrelevant to him, he just reaps all life, everywhere.

Also maybe cares about more than just life as we define it. On his grand scheme he could concern himself with the "life" of stars of galaxies. He could preside of matter in the universe and watches as matter itself deacys (why would death care more about this lump of carbon with sentience than that lump without; it all breaks down and he'll "reap" them both eventually).