Zeths

Zeths are a fictional species appearing in the science fiction novel "The Expanse" series by James S.A. Corey. They are an ancient, highly advanced alien race that has long since departed the Milky Way galaxy, leaving behind remnants of their technology and influence. Zeths are not encountered directly by the human characters in the series but are a significant historical presence. Their primary contribution to the narrative is the protomolecule, a powerful and complex alien substance that serves as a central plot device. The protomolecule is believed to be a tool or creation of the Zeths, designed for terraforming or other large-scale biological engineering.

The Zeths are described as having a very different form of existence compared to biological life as understood by humans. Little is known about their physical appearance or societal structure, as the available information comes from the study of their artifacts and the protomolecule itself. Their motives and ultimate fate remain largely a mystery throughout the series, driving much of the exploration and conflict as characters attempt to understand and control the protomolecule and its implications. The Zeths represent a profound unknown in the universe of "The Expanse," serving as a testament to the vastness of space and the potential for life beyond human comprehension.