The Forebears were figures that existed in Benzite mythology.
According to the Benzites, their race descend from a currently extinct species that came to Benzar from another world when they quickly realized that they were unable to survive in the planet's harsh environment. The Forebears attempted to create a species of intelligent lifeforms that were capable of not only living on Benzar but prospering in its planetary conditions which eventually became the race known as the Benzites. While this was occurring, the Forebears themselves succumbed to the toxic environment.
Many wonder why such an advanced race that was capable of engineering an intelligent species was incapable of sustaining their own existence, however, such discussions are rarely asked of the Benzites and, as such, remain a mystery that the race are unwilling to explore. Their legends on the Forebears contains mystical significance to the race and consider those topics to be sacred as well as taboo to discuss.
One of the artifacts of the Forebears are the Birthing Chambers that the Benzites continue to use to this day. (Decipher RPG module: Aliens)