#4. LEVIATHANS
We may never actually have seen the Leviathans, and they’re more crucial to the series’ lore and backstory than they are to the present narrative- but given how fundamental they are to that narrative and how compelling the lore attached to them is, we can’t help but give them a pretty high place in this list. The Leviathans are, after all, the creators of the Reapers. Not only that, they’re also perhaps the oldest alien race in the series that we know of. They ruled the galaxy long, long, long before anyone else did, made advancements unlike any other, and dominated entire worlds and species, with their empire spanning pretty much the entire galaxy. Fittingly enough, it was the Reapers themselves that brought about their downfall- speaking of which…
