Optem

The Optem, also known to the Covenant as the Looters, are or were an Ulterior civilization known to the Covenant. They seem to have showed a particular interest in Forerunner artifacts, and visited various Forerunner sites within the Orion Arm circa 20,000 BCE, stripping those relics of useful technology and data. No contact has ever been made with them, so it is not known whether they remain active in the galaxy.