Alien (The 27th Day)

This unnamed humanoid species sought refuge from the death of their homeworld, and tested Earth's qualities by giving Humans the ultimate superweapon.

Biology
The aliens appear externally indiscernible from Humans, and Earth's environment is hospitable to them, ideal for them to colonize. Any differences in physiology are unknown.

Culture and society
The aliens are pacifists, refusing to turn any weapon against an intelligent species, to the point that they are willing to let themselves die rather than directly hurt another. However, when testing the character of another species, they are willing to provide that species with weapons of mass destruction, seeing whether or not said species is willing to use them for conquest. To properly test a species, they select members of the general population at random, not necessarily anyone in power or of importance. They will not intervene throughout the testing process. Alien attire is known to consist of reflective, dark, long-sleeved jackets with matching pants and boots.

Technology
The aliens have highly advanced technology, capable of flying through space at lightspeed with saucer-shaped spacecraft. While in flight, time within the ship accelerates to the point that several minutes can pass aboard them in the time it takes for the second hand of a watch to move. These spacecraft have at least one circular chamber within them, capable of holding several passengers, equipped with a viewport in its center, semi-spherical lights, and semi-transparent walls. Items can be sent to the room by a hovering ring, which descends from the ceiling. The aliens have also developed universal translators, allowing their speech to be heard in the native language of whoever listens to them, and can override Earth-tech electronic communication equipment to make broadcasts. One of the most notable feats of alien technology are capsule-like devices serving as weapons of mass destruction, capable of incinerating lifeforms of a specific species within a 3,000 mile radius. These capsules come in clear containers only able to be opened and closed by the thought-waves of select people, holding three capsules each. If the select person commanding a capsule were to die before the capsules could be used, the capsules will self-destruct. Once opened, the capsules are activated by voice command, receiving longitude and latitude coordinates from the user and then releasing its destructive power from the center of that area. While only a select person can open the container of the capsules, the capsules themselves can be used by anyone. The capsules can also be reprogrammed using a mathematical code imprinted on them, allowing them to target specific individuals rather than destroying indiscriminately, and deactivate if left unused for a certain period of time. Due to the aliens' moral code, it is possible that these weapons were repurposed from another device not meant to be a weapon, or made specifically for Earth. In addition, the aliens appear to have some form of teleportation technology able to beam lifeforms to their ship in a flash of bright light.

History
At some point prior to the mid-20th century, the aliens' home star system was dying. To escape the destruction, the aliens took off into space, seeking a world to evacuate to, finding Earth in the mid-20th century. Earth was an ideal world to colonize, but the aliens saw the intelligent life on the planet's surface, Humans. Observing the Humans for a while, seeing the world locked in the Cold War and seeing Human history rife with destruction, they decided to test the true qualities of Humanity, developing superweapons to be used in the test, and selecting random civilians from across the globe. A nameless representative of this species appeared to the select individuals, consisting of Evelyn Wingate of England, Jonathan Clark of the United States, Su Tan of China, Klaus Bechner of Germany, and Ivan Godofsky of the Soviet Union, teleporting them to his ship, which promptly left Earth. The Humans were gathered together in a chamber aboard the ship, where they tried to process what had just happened. After finding out that they were all from different parts of the world, they were met with the representative, who introduced himself as "The Alien" for simplicity, as he was a stranger to everyone present. He then explained that the Humans are representing their race. When questioned as to why he came, The Alien explained that they could not let Earth be destroyed by Human weapons, as his species' home system was dying, with their star going to explode in 35 days, and they need Earth for a new home. However, The Alien said that his species' moral code would not let them invade, instead, they would provide the Humans a weapon that would only destroy Humans, and would thus leave the planet unharmed if used. Humans were to keep the weapon for 27 of the 35 days, following Greenwich time, and if the weapon remained unused, it would deactivate. The Alien admitted that while his people expected the Humans to inevitably use the weapons, they will not hope for disaster, merely let events play out. In addition, if the weapons remained unused at the end of the 27 days, the aliens would leave Earth, and die in space. After giving an explanation of how to activate the weapons, claiming that they had the power of both life and death, The Alien assured the Humans that his species would remain true to their word, then sent the Humans back to Earth with the capsules, in the same spots from which they were taken, where no time had passed at all.

Shortly after the Humans were returned, The Alien tapped into all electronic communication systems on Earth, telling the planet's population of the superweapons, and naming all the Humans who he had given the weapons to. The Alien's broadcast prompts panic over the following days, and intense manhunts for the Humans who were given superweapons. The aliens remained in space, watching the planet, as on the ground, Su Tan committed suicide, while Bechner, Clark, and Evelyn eventually cooperated with the US government, and Godofsky was forced to grant the Soviet government access to his capsules. With twelve days left, as the Soviets attempted to use the capsules for world domination, Bechner figured out The Alien's true intentions of testing Mankind's character, remembering The Alien's words of "life and death," realizing that the capsules could be used for more than just mass destruction, the same way nuclear power could be used as an energy source rather than for warheads. Soon, he managed to find a code imprinted on the capsules, one that enabled them to be reprogrammed, just as a Soviet general was going to destroy all Human life in North America. With Bechner's new knowledge, and a timely intervention from Godofsky that prevented the Soviet general from activating the capsules, Bechner had the capsules launch a high-pitched sonic wave across the planet, targeting and killing anyone listed as a confirmed "enemy of Human freedom," including the Soviet general. In the wake of the event, Humanity was unified under the United Nations, and Bechner sent a message to the aliens, inviting them peacefully coexist with Humans. The Alien responded, accepting the offer and telling Humans of at least 30,000 more inhabited planets that they could help Earth contact, beginning a new age for Humanity.

Appearances

 * "The 27th Day", by John Mantley (1956)
 * The 27th Day (1957)