In Isaac Asimov's Foundation, a
Foundationer was a member of the intellectual elite who would bring
about the Second Galactic Empire. Members of the Foundation (a.k.a
the First Foundation lived on Terminus and were masters of the
physical sciences. Members of the Second Foundation were masters
of the mental sciences.
Warning: spoilers!!!
Although the Second Foundation (which remained on Trantor after
the fall of the First Galactic Empire) believed themselves to be
the true Masters of the Universe, they too were subject to the
subtle, external control of the robot R. Daneel Olivaw.