So, I notice trolls aren't listed up here yet. This needs to be fixed.

Trolls are grey-skinned humanoids with candy corn colored horns, sharp teeth, and yellow eyes. Their blood runs a gamut of rainbow colors, which denotes where you fall on the social ladder. Trolls come in two flavors: land- and sea-dwelling. Land-dwellers are your average, run-of-the-mill trolls, whereas the sea-dwellers are typically nobility, with fins, gills, and blood that runs up on the higher end of the hemospectrum.

Trolls are generally more aggressive and violent than humans, both due to their culture and their natural instincts (although this isn't the case for everyone, obviously). Some also have psychic abilities -- Sollux and Aradia are telekinetic, and Vriska is able to manipulate people's minds.

You will also have ridiculously complicated romantic entanglements. No one will have any idea what is going on at any given time. No, not even you.