Halo kinda struggled to find an enemy faction that would stick as much as the OG Covenant and the Flood after its initial trilogy, but I think the series hit a homerun with the Banished, a rogue alien group exploited by the original game's big bad who also happens to be led by an ultra badass brute. Though the faction was only created to get back to the series' roots after Halo 4 was a little too dark and Halo 5 was... well, bad.
Speaking to FRVR, Halo Wars 2 writer Dion Lay explains that 343 Industries (now Halo Studios) came up with the idea for the Banished to introduce in the RTS sequel, laying the groundwork for them to take center stage in Halo Infinite.
