Do We Have This? Needs a Better Name. Sometimes, it's considered a mark of good World Building in the Science Fiction genre to develop an alien culture like you would any aspect of the story. To talk about their history, culture, motivations and character. Other times, writers find it best to leave these questions for the ages. The aliens are simply there. Any attempts at communication are met with silence. Their origins, motives, and plans are all mysterious. Nothing is known about their society and culture. Their actions come across as bizarre, incomprehensible, and frequently terrifying. This trope is common in invasion literature and Horror, in order to add to the "other-ness" of the aliens. Often the aliens in question are Starfish Aliens and may speak a Starfish Language.
- Independence Day: The aliens just show up and blow up cities, the only time they communicate with humans is when one is taken prisoner and take telepathic control of a scientist in order to demand its release.
- The aliens in Battle: Los Angeles don't make any attempt at contact before they crash in and start killing people.
- As with many Alien Invasion trope, the trope codifier is probably War of the Worlds.
- The Ender series has a word for such a species: varelse. More than one of the species placed in this category were later reclassified as the understanding between them and humans improved.
- The Ark Megaforms in Space Mowgli, though they do attempt to communicate with humans via the title character.
- The Wanderers in the Noon Universe novels: humanity finds traces of their presence all over the galaxy but has never encountered one in person.
- Variation in Blindsight. The alien ship does make contact but the crew quickly figure out that they're talking to a "Chinese room". They spend a lot of the novel trying to figure out whether the giant starfish-like creatures patrolling the ship are sentient or just drones of some kind as they make no attempt at communicating. The truth is far more sinister, the aliens are not sentient, self-awareness is not required to build starships, sentience is an anomaly unique to H. sapiens sapiens and will be corrected
- John Wyndham's The Kraken Wakes (AKA Out of the Deeps). A group of aliens invades the Earth's oceans. They never contact the human race in any way and the two sides engage in a war without either side ever seeing the other face-to-face.
- Robert A. Heinlein's short story "Goldfish Bowl". Unknown creatures (it's not clear if they're from Earth or aliens) suck a huge pillar of seawater into a cloud and then return it to the ocean. They also send out fireballs that kidnap people. They're never seen by humans and don't communicate with humanity.
- Stewart Cowley's Spacecraft: 2000 to 2100 A.D.. The City Ships of Alpha are huge cities that float from one pillar to another at irregular intervals. They have existed as far back as the Alpha Centaurians' history goes. All attempts by the Alpha Centaurians to communicate with their occupants have failed, and all attempts to enter the cities are prevented by a protective force field.
- The contagion embedded in the deep space probe in The Andromeda Strain is a crystal-based organism that kills Earth creatures by reorganizing the minerals in their bodies to fit the crystalline template. It turns out, the crystals have predefined stop points, leading to the hypothesis that the organism was created by an extraterrestrial intelligence as a data storage medium.
- Star Trek
- In the Star Trek: Enterprise episode "Silent Enemy," the Enterprise encountered a species that answered hails but did not speak, and soon turned inexplicably hostile.
- An episode of Star Trek: Voyager had them rescue an alien that was so bizarre they had to start from scratch on trying to understand it. Its biology was such that the medical computers, including the Doctor, couldn't make sense of it, and its language was beyond the universal translators capacity to decode.
- In another episode, Voyager itself played this role. They were in orbit around an unknown planet. Unbeknownst to them at first, time passed much faster for the inhabitants of that planet, so from their point of view Voyager had been in their sky for centuries, and was a complete mystery to them.
- The Stargate SG-1 episode "Grace" had the Prometheus encounter a ship which refused to respond to hails and opened fire on them, chased them into a Negative Space Wedgie which trapped them both, and abducted all of the crew save Samantha Carter. Even after Carter manages to figure a way to get everybody out (using a hyperspace "bubble"; It Makes Sense in Context), the alien ship doesn't respond to her when she hails it to demand the return of the crew in exchange for help; it just teleports the crew back.
- Stargate Universe had the crew aboard the Destiny chased by a Starfish Alien species (dubbed the Nakai by executive producer Joseph Mallozi) that only transmitted the word "surrender" as a constant enemy, and the crew ends up finding little (if any) information about them during the course of the series.
- The Vorlons from Babylon 5. While they can be spoken to, it's debatable whether they can be communicated with.
Sinclair: Yes we have files on them, very large files. There's nothing in them, of course.
- The Mothership Zeta expansion of Fallout 3 features the player character fighting his way through an alien space ship. We hear a variety of accounts of (horrifying) experiences with the aliens from a number of people, but the human characters can only guess at the aliens' motives for the atrocities they commit.
- The X-Universe series has the Khaak, a species with point-to-point jumpdrive technology that invaded the Community of Planets in X2: The Threat, and was finally defeated midway through X3: Terran Conflict. No attempts to communicate with them have gotten a response, prompting speculation in-universe that they're just too mentally alien. All the Community of Planets races have learned is that they are attracted to nividium and that they seem to be Bee People rather than individuals.
Hello, Unknown Troper. You'll need to get known to lend a hand here.