The colloquial name given to a approximately humanoid species that colonized a volume of space roughly coincident with that of human space, but tens of thousands of years before mankind. Until recently, only scanty archeological evidence remained of their presence.

IN 3212, a major find was made as a result of research conducted under the auspices of the International Forerunner Foundation, an unmarked world, now known as Mystery, which may be one of the original Forerunner Homeworlds. Shortly after this historic find, two more 'homeworlds' were located.

Mystery is now the most important site for Forerunner Archeology, and work has virtually ceased on all the more minor sites accross human space as Mystery represents the greatest single source of materials - probably a thousand times bigger than every forerunner find ever uncovered throughout human space put together.