Sectoid

Sectoids (Metanthropus roswelli) are one of the most common and widespread of aliens introduced to, characterized by their relative physical frailty, origin as a designer organism, and natural aptitude for Psionics. While having large and advanced  skills in advance of, their neural architecture is radically different, with their  being proportionally larger and denser than the rest of the brain in comparison to both humans and other sapient aliens. Sectoids, like humans, have a high degree of, although their unique penchant for psionics has shown some degree of , with some likening their society to a sort of limited 'hive mind', though thanks to the introduction of human genetics, a wider range of expression has been observed.

Unlike most forms of sapient life, their biology is inexorably tied to their recent history, as their overall presence as living beings is seemingly brief in comparison to all other alien life forms encountered by humans. Sectoids have their origin in the Zudjari civilization, being initially created through as a replacement for Zudj labor within their empire, essentially functioning as a bio-mechanical. The species' first known appearance on Earth was in 1947, as part of the, including a recovery of Sectoid bodies and a damaged scout craft from. Between 1947 and 1962, Sectoids which had been left behind by the scouting expedition began establishing forward operating bases in isolated areas of the United States, each containing cloning facilities which allowed for the manufacture of new Sectoids, as they had no means of natural reproduction, alongside phase plotters which connected facilities to Mosaic, which allowed them to utilize their psionic abilities, as they lacked the natural architecture to engage with each other psionically without its presence at the time. After the killing of Origin and the takeover of Mosaic by the CIA-SEC at the conclusion of the First Secret War, what few Sectoids remained were forced to dismantle their cloning facilities and fled Earth alongside the surviving Zudj following the conclusion of Operation Farewell, but were aided in an apparent slave revolt by the Cydonians, who developed the Sectoids' natural psionic aptitude in exchange for their service. Their morphology was otherwise unchanged since their initial creation, and remained as such following the destruction of Cydonia during the Second Secret War up through the War of 2015 when they were under the employ of the Elders. Following the conquest of Earth, human genetics were incorporated into the Sectoid genome to 'stabilize the species', essentially turning them into a posthuman alongside the Hybrids, starting in 2016.