Domestic Outerfolk

Those considered domestic Outerfolk are those who, either directly or under the authority of another, serve the ends of the Colossi. Even very minor members of the Metabiotic Outerfolk actually serve their leaders' goals, and only tangentially those of the Colossi.
Most numerous of the domestics are the Xvarts; odd, blue- skinned humanoids possessing but a single face between them. xvarts are, in fact, a form of construct, intended to provide a bridgehead for more powerful servants. They are created by projecting the power of the Colossi into the World, through the Voidskin, where they are generally programmed to perform simple, ritual tasks intended to open gaps in the defences created by the Gods.
The derro are mortals utterly corrupted by subterranean Void flux concentrations. Almost as pathetic as the xvarts, they are burdened with compulsions, but with little recompense in power or favour. The Merrow of the deep oceans are the aquatic version of the derro.
Derro and merrow alike are part of a larger grouping, known as the changed, the corrupted, or the spoiled. Such creatures are all transformed - personally, or as part of an infection of other bloodline - by the destructive power of the Void.
Spawn are - probably - the blasted souls of those who enslaved themselves to the Colossi as their worlds burned, seeking to save themselves. Through the labour of derro and xvart, or of misguided cults, these soul-remnants become mere animating drives for bodies formed of elemental energy. The star spawn are clothed in air, core spawn in earth, and deep spawn in water, while the rarest of all, the ash spawn, are birthed in fire.
The tamed is the collective term for Phoresic Outerfolk who have been subborned to the service of the Colossi, including creatures like neogi and intellect devourers. The category is often extended to cranium rats, which are technically corrupted, regular rats altered by Void energy.