The Forerunners are an ancient species that once ruled the galaxies. They had many colonies and prospered. They fought the humans which led to a bigger threat the flood which caused their demise. Generally they were peaceful and vegetarians. When attacked, they are extremely aggressive. They were killed off by the firing of the Halo rings. They are responsible for much of the reason why the Human-Covenant war occurred. Danny-048 is a Forerunner hybrid which he newly discovered. The UCR has had various interactions with Forerunners, usually nonviolent, unlike the UNSC. The UNSC generally finds itself at odds with Forerunners and their abandoned installations.