Shapeshifter (Chameleon)

The shapeshifters are an unnamed alien species capable of assimilating lifeforms and shapeshifting into both living things and inanimate objects.

Biology
The shapeshifters are capable of reconstructing their bodies to perfectly mimic any living being or inanimate object, doing so in a flash of light. They are also capable of assimilating both lifeforms and objects, and any lifeforms that are assimilated have their memories also assimilated, granting the shapeshifters potentially unlimited knowledge. Assimilation appears to require physical contact to be achieved, and creates a bright flash of light that seemingly disintegrates the targets. Objects they mimic are able to function just like a regular version of the object would, even if they are as complex as an atomic bomb, although the shapeshifters require extensive knowledge of what they are shifting into to create such a perfect mimicry. This is can be achieved by assimilating the memories of someone who has such extensive knowledge, a tactic which can be used to create images of other living beings that they have not seen or assimilated.

Assimilated lifeforms appear to not have their consciousness destroyed, but rather, implanted into the shapeshifter's mind, remaining some degree of individuality. Instead of fighting back, assimilated minds appear to be manipulated into willingly staying with the shapeshifter, with the shapeshifters claiming that the "thirst" of the assimilated minds, possibly just curiosity, is what causes them to stay. In addition, the shapeshifters are able to transform into non-solid forms, such as a gaseous form, allowing them to travel through space at possibly speeds approaching or even surpassing that of light. The true form of this species is unknown, but is possibly gaseous or energy-based by default. In a solid form, the shapeshifters are capable of easily overpowering and restraining adult Humans.

Culture and society
Little is known of the society of the shapeshifters. They appear to see no wrong in assimilating sapient lifeforms, appearing to believe that they are doing said lifeforms a favor by allowing them to travel across space with them. If they are captured, they will attempt to bargain with their captors, and if the captors continue to refuse to free them, the shapeshifters will resort to trickery or force to escape, even threatening their captors with weapons of mass destruction, formed from their own bodies. They appear to be either intergalactic nomads or scientists, possibly both, going to different plants, observing and assimilating lifeforms, on what they claim to be mere curiosity. They do not appear to utilize any technology of their own creation other than what they assimilate.

History
At some point in the late 20th century, a shapeshifter arrived in Earth orbit, assimilating a camera on a US space shuttle, causing it to malfunction and get shut off. When the shuttle lands, a Human technician named Simmons examined the camera, only for the shapeshifter to assimilate him, seemingly disintegrating him. His colleague, Tyson, sounds the alarm and has the camera quarantined. The shapeshifter, held captive in an isolation chamber, transforms into Simmons and demands that the scientists free him. When the scientists refuse, the shapeshifter uses Simmons' memories to shapeshift into Simmons' wife, but when still not released, the shapeshifter turns back into Simmons and begins destroying samples. The scientists attempt to subdue him with sleeping gas, which appears to subdue the shapeshifter. However, when another scientist named Dr. Heilman enters the chamber to give another sedative to the shapeshifter, the shapeshifter gets up and assimilates Heilman, utilizing the doctor's knowledge of nuclear bombs to create a live warhead, which slowly ticks down. A scientist named Lockridge communicates with the shapeshifter and agrees to free it, opening the door for it to leave. When the timer ticks down to one second, the shapeshifter turns back into Simmons and quickly exits, with Lockridge confronting it outside the facility and demanding that it release the assimilated Humans. The shapeshifter claims that the Humans are willingly staying with it, and then offers a chance for Lockridge to be assimilated and follow the shapeshifter throughout the vast reaches of space. Lockridge refuses, and the shapeshifter turns into a gaseous form to leave into space.

Appearances

 * The Twilight Zone, s01e02c, "Chameleon" (1985)