Centauri Knights is a campaign setting for the roleplaying game Big Eyes, Small Mouth. It was written by David L. Pulver and published in 2001 by Guardians of Order. It is a science fiction setting centered on Osiris, a planet orbiting the star Alpha Centauri, and contains many transhumanist themes.
In this setting, interstellar travel is a new technology and requires human space travelers to be transplanted into cyborg bodies. The first human explorers to reach Osiris found the remains of a civilization and species that had been destroyed by a grey goo incident. The Osirans were users of nanotechnology, and humans known as "Fog Witches" are able to manipulate the nanomachines that are still in the atmosphere. The campaign setting centers around exploration of the ancient Osiran culture, the conflict between the Earth government and independence-minded colonists, and a cultural rebellion in which human colonists adopt Osiran ways.
A d20 System version of this setting was published in 2004.