The Sen'kaal (Chalic: SSeN'Kaalen) are a species of aliens first contacted by humans on July 11, 1957 and defeated by the UN in the Human-Sen'kaal War of 1957. They have not been seen in UN space since then.
The Leadership Forms (The Ruling Castes)
The Sen'kaal are ruled by a single leader, known as the Dominarch. It is unclear exactly how the Dominarch is selected. The Dominarch has final authority on all matters, and captured Sen'kaal records seem to suggest that he (or possibly she, although the only Dominarch that mankind has encountered was biologically a male) rules for life. The Dominarch can be deposed through a ruzh'kalat, or "ritual slaying," where the Dominarch's advisors, the Khulai, assassinate him. This is considered acceptable in Sen'kaal society. The Dominarch, upon accession to the position, abandons his name; and, for the remainder of his lifetime, is referred to by a number (for example, the twelfth Dominarch would become Dominarch 0012). Dominarchs are biologically different from all other castes, and it is believed that, in order to become Dominarch, a Sen'kaal must undergo biological and genetic modification. The procedures appear to result in the Dominarch-to-be losing their ability to tap into the Nexus.
Physically, the Dominarchs are much taller and stronger than any other caste of Sen'kaal (with the exception of the Rho'da'kal, or Titans).
The Vaktorians are the next most powerful beings in the Dominarchy, after the Dominarch and the Khulai. The Vaktorians appear to be biologically different from the other Sen'kaal castes, and are believed by many to be a different species that was assimilated into the Dominarchy due to their very high intelligence and ability to tap into the Nexus. UN intelligence reports seem to suggest that the Vaktorians serve as a "bridge" between the Dominarch and the rest of the Dominarchy. Dissections of Sen'kaal corpses seem to indicate that Nexus-sensitivity is not a natural feature of the Sen'kaal race, and that all Sen'kaal are crossbred with Vaktorian genes to make them Nexus-sensitive.
Physically, they have elongated mandibles, glowing eyes (always green), and glowing marks on their faces, which are usually shrouded by maroon hoods. They wear maroon robes.
The Prakton are the military leaders of the Dominarchy and are appointed by the Dominarch. Each Prakton commands a Warfleet. It is believed that at least five Prakton and their respective war fleets were involved in the assault on Earth.
Physically, they are very strong. Prakton have a third eye and a second pair of thin legs branching off backwards from their hips. They also usually have vestigial wings.
The Basic Combat Forms (The Soldier Castes)
Numerically, the drones are believed to be the largest Sen'kaal caste, with the sole exception of the larva. The drone, (or the grunt, as UN forces nicknamed them) is a light, fast, versatile, but fairly unintelligent caste. Combat experience has shown that the drones' connection to the Nexus is weak, and, as such, all drone units are accompanied by at least one Nexus Mage as a sort of a "signal booster."
The Nexus Mages (also called Psychers and Nexians)
Nexus Mages serve as low-level battlefield coordinators and commanders, relaying Nexus commands to Drones and other units. Physically, they are somewhat stronger than the Drones, Wasps, and other units that they command. They have somewhat lighter exteriors with small yellowish-brown spots and blotches.
(More to come later.)