Alien Species

Quelthonian-

Draconians-  Reptilian aliens originating in the Draco system.  First species encountered by Humanity, part of the Triple Alliance with the Mantis Empire.  Draconians are war like but noble.

Mantis-  Insectoid aliens originating in the Mantis system, they are the most ancient known species, having the most advanced technology and being the most advanced technological species, they provided the Draconians and later the Terrans with Singularity Technology.

Silicate-  Silicone based aliens from a distant star system, dubbed Silica Prime, they are the main adversary of humanity as they share no common resources and cannot coexist easily.  The main intelligent species of Silicates (Silicate bio spheres contain billions of distinct silicate species, much as any carbon based biosphere would) called the Kairn, run an empire known colloquially as the Silicate Empire.  They invade Organic space on many occasions.

Lychanid-  Another alien species from a distant star system.  An ancient cosmic civilization which genetically engineered itself into a hive mind resembling fungal organisms from Earth.  The Lychanic Collective controls millions of worlds and has the ability to assemble massive armies of grown troops and armada's of living starships, giving them the ability to counter any known military in the Galaxy. 

Slimeblob-

Crystaline-

Xetan-

Quadrian-

Artilect-  Any AI organism, a brain of electronic origin which rivals organic intelligence.  Can scale from small AI's which we would know in our modern world to massive planet sized computer which can compute to the scale of humanities collective brain power every second.  Also more connected to the code/continuity vs the physical computer an Artilect inhabits.  Continuity is everything.

Symorphic-  A being which has altered itself to be partially one species or form, and another.  Any combination form of alien/human/animal/plant.  Socially acceptable going into the future, some people have photosynthetic skin meaning they can live without eating on just sunlight, the first major Symorphic population.  Later people take on animal forms or characteristics, or transition between bodies/species, a symorphic could be anyone between forms of any kind or who had fully transitioned.

Metamorphic-  Someone who has transitioned their physical body (Besides mind/nervous system)  into a swarm of nanites.  They can shapeshift at will.  Due to the possibility of abusive behavior, Metamorphics are very socially unacceptable, though somewhat common.