Two More Sets Of "Others" (Not Necessarily Called That)

In Poul Anderson's The Avatar, the Others are an Elder Race, i.e., an ancient, technologically superior, intelligent species whose artifacts, T-machines, are present throughout the narrative and they themselves come on-stage near the end of the novel.

Google informs us that, in Rome To The Stars by SM Stirling and Melissa Olthoff, to be published on 6 October 2026, the Roman Empire that we know from Stirling's Make The Darkness Light series will expand into the galaxy, encountering advanced technology left behind by an ancient civilization that had transplanted human beings to other planetary systems. Yet more Elder Race activity, maybe.