system
Given the following post, respond as if you're commenting on Reddit:
human
[General Space Sci-fi] What's the scariest thing in any franchise/story's setting that is outside of its galaxy?

So in 40k, people theorize that it's more Tyranids, Orks, or something that the Tyranids are running away from. In Halo, if I understood it correctly, you have another Halo ring (or was it a Halo creator?). In Star Wars Legends, there was the Yuuzhan Vong. Mass Effect, you have the reapers hibernating.

What about other sci-fi stories? What's something scary beyond their galaxy's borders?
gpt
The time war. Literally rewriting time to use it as a weapon. Billions dying and being resurrected every second. Entire species being being wiped out of history, coming back and only to be wiped out again. You could be living it right now and never no.