Sentinel

Sentinel - A position found among Nokkar’s people, in their intergalactic war with the Space-Spawn. A Sentinel is a member of their race who is posted to a planet, as Nokkar was to Earth, to keep watch there and defend it from the invaders. Sentinels are not permitted to take prisoners, but are presumably (from Nokkar’s own experience) allowed to work with the local inhabitants of that planet.