Narguls/Noggles/Nargles

Either

• the elite, advanced race Reb Itto believes used to inhabit The Empire of Coraar 'ath Revaar, who could shoot lasers from their eyes

Or

• Creatures found mentioned in a book in the library of Aglarond, The Glittering Chambers which seemed to belong to The Dreabig

Or

• Both

Apparently a race that lives in Davokar before the elves of The Empire of Coraar 'ath Revaar, who also had an empire that had similar aspirations. (Source, a convo between Reb and Qwyns family. It is unclear whether Qwyns family directly interacted with them but it is implied they'd have known who was in The Waking as they'd have fed off their emotions. Also unclear if they were trolling us.)
This has been backed up by the ghost of Councillor Jinra Ingea, who seemed to know for a fact that there had been a previous civilisation in the forest, but as far as they knew, they had been long dead by the time the Elves moved there. They regarded them as irrelevant to their work (which was diplomacy with alive people) and so didn't know much more about them.