Precursor

The Precursors are a mystery to Halo fans as of now, though the picture taken of the leaked Beastiarum names a new race -- The Precursors -- as a race mythologicized by the Forerunner, being theoretical "Transsentient" beings. The Precursors are believed to have achieved Tier 0 (Transsentience) on the Forerunners' Technological Achievement Scale.