This is an article about the alien race from the X-COM universe. If you're looking for similar real-world rumor aliens, see Grey.
Sectoids is one of the master races that fight against X-COM during the First Alien War. It is a physically fragile race, with skinny-hairless body, large head and oversize eyes, not unlike the Grey. Although the brain and eyes are very well developed, its small mouth and nose appear to have little function It also lacking reproductive organ, this is because the aliens are genetic altered and rely completely on the cloning method.
They're the vanguard of the alien force, a low-ranking sectoid is the weakest alien encountered by X-COM. They're weak, walk slowly, not good with weapons and even mundane pistol can kill a sectoid in one shot. Web between its fingers and flat feet are sign that they are descendants of the Aquatoid which humanity would later encounter in the Second Alien War.
Although sectoid soldiers are weak, the sectoid hierarchy is define by psionic ability. A high-ranking sectoid can use its psychic powers to demoralise soldiers in combat, or even take control of their minds.
They tend to indulge in human abductions and cattle mutilation. The abduction is used to extract genetic material for cross breeding and developing clones for infiltrating human society. The cattle provide both nutrition and genetic material. Apparently, sectoids want to develop superior genetic hybrids to increase the efficiency of their hive-like society. The crossbreed between humans and sectoids are genetically almost identical to humans but retain some alien facial characteristics and high psionic ability. These hybrids have survived in human society, but often distrust by humans.
Sectoids also use mechanical robot known as Cyberdisc. No one knows why Sectoids are always naked, but its speculated to be that sectoids don't like clothing, which is irrelevant to its size.
After Earth is subjugated by the Ethereals and the ADVENT administration, Sectoids are augmented through the use of Human DNA spliced into their genome. As a result, these Sectoids have become taller, stronger and with greater psionic power.