Precursor
From Halopedia, the Halo wiki
The Precursors are a mystery to Halo fans as of now, theBeastiarum names a new race -- The Precursors -- as a race mythologicized by the Forerunner, being theoretical "Transsentient" beings.[1] The Precursors are believed to have achieved Tier 0 (Transsentience) on the Forerunners' Technological Achievement Scale.