This trope applies to creatures which may or may not be robotic. They usually appear to have artificial mechanisms behind their creation, or perhaps they have what appear to be robotic parts connected to (or growing from) their bodies. Then again, they may have fur, or be salivating or perhaps move in a fashion too animalistic to be considered robotic.
In short, the viewer will wonder "Cyborg, or machine with organic parts?"
The ambiguity between machine and creature is never resolved. In fact, most of the time, it is never even mentioned. Often, it is deliberately creepy.
May be related to Mechanical Lifeforms.
- In Neon Genesis Evangelion, the giant mechas turn out to be not only organic but also forcibly trapped in the mech suits, in order to limit their power.
- Also played straight, what with the external power sources and lack of any clear definition of where the Eva ends and the cybernetic bits begin.
- In Eureka Seven, the LFO's (Light-Finding Operation) and KLF's (Kraft Light Fighter) are organic with armor and control mechanisms added on. They find the templates in mines, conveniently shaped to be one seater mecha (although at least one has a tandem cockpit). The Nirvash is unique both because it was the first one ever found and because it is explicitly shaped as a pair (next to each other, not one behind the other) two seater.
- Section 9's cyborg police from Ghost in the Shell. Are they humans with cybernetic implants or robots with organic parts? They even wonder themselves.
- Alien: Perhaps the most famous example. Is it organic? Who can tell. It is shiny metallic, with wires and tubes and acid instead of blood. The ambiguity in this example adds to the mystery and haunting power of the film.
- Beyond the Xenomorphs, we also have the Space Jockey from the first film. The androids (Ash in the first movie, Bishop in the second movie) are a borderline example. They seem to tend toward robot, but any time they're wounded, we see some inhuman-but-possibly-organic guts.
- The Kaleesh cyborg, General Grievous, from Star Wars gets this treatment from both the audience and people in-universe. In fact, his Berserk Button is when people call him a droid.
- The Replicants from Blade Runner. They appear to be organic, but are they robots or genetically engineered humans? We never really get a look at their insides.
- Isaac Asimov wrote a short story concerning a hunt for a lost planet that functioned as a psychology experiment. Robots, "with much simpler bodies than our own," were implanted with the laws of psychology and were unknowing of their status as robots. Right up until one of the cities on the planet is mentioned, New York.
- The Hitchhiker's Guide to the Galaxy raises similar questions about Earth. Since it was part of a computer designed to find the ultimate question of Life, The Universe and everything. The answer to which we already knew was 42.
- Bioloids in Farscape: Bio-robots or artificially constructed cyborgs? It's hard to tell. Similar to the example of the Androids in Alien, in that they are clearly artificial, but their inner workings appear to be at least partially organic and their name only reinforces this ambiguity.
- Also, the Coreeshi bounty hunters. They permanently graft themselves into their bio-mechanical looking armored suits (making them very similar to Cyborgs), and what we saw of their true form (we think) was a viscous orange goo. However, a Scarran spy was also able to graft himself surgically into such a suit.
- The Cylons in the original 1970s Battlestar Galactica started out like this: the original idea was that they were reptilian beings in armored robot-like suits, but that idea got nixed when they were established as the robotic descendants of a reptilian race.
- Bionicle: For the first few years, it seemed that most of the characters were Mechanical Lifeforms, but they were later revealed to have some organic components such as muscle and lung tissue (meaning they're technically cyborgs). An outsider later commented that they move too fluidly to be pure robots. Just to highlight this trope, there's another setting where the ratio is reversed: characters are mostly organic with some cybernetic enhancements. Yet, thanks in part to wearing heavy armor, the mostly-organic characters don't look much different from the mostly-robotic ones.
- Note that how this is depicted in different media is very varied. Only the first three Direct to Video movies went out of their way to actually show muscle and other kinds of tissue. In the fourth (starring the mostly organic character variants), they are all completely mechanical in appearance. It has been hinted at that the creators of said movie simply had no idea what kind of beings they were making a movie about.
- The toys weren't of much help in this matter. The action features required them to have all sorts of gears inside them, and it wasn't until the Voya Nui saga (2006) that the first and only figures with actual rubber muscles came out (there are also rubber collectibles like Kraata slugs or sea squids, but those aren't technically figures). And even those only had rubber on certain parts—the Piraka on their face and back, and the Toa Inika wore fleshy rubber masks.
- Necrons from Warhammer 40,000: They look like skeletal robots, but are apparently more Haunted Technology or metal golems, or whatever.
- Eldar Wraith-warriors are made of psycho-sensitive wraithbone, which is as hard as adamantium, but isn't constructed, but rather "grown" through the use of a bonesinger, who literally sings to the material with a psychic song, causing it to be shaped into whatever is needed. Wraithbone itself is said to be solidified psychic energy, so it's all up in the air about exactly what Wraithlords and Wraithguards are technically.
- The Phyrexians of Magic: The Gathering get here from both roads. Phyrexian dogma holds that the flesh is inherently imperfect and must be upgraded to stand "compleated" in Phyrexia's embrace; similarly any non-Phyrexian machines are pale imitations of the glory of Phyrexia and must be made suitably Phyrexian, which typically includes at least a few biological extras.
- Shadow of the Colossus: The Colossi are either gigantic robots of stone, or huge hairy monsters. The mechanical faces of the Colossi are clearly artificial, but parts of their bodies are quite biological. Again, this contributes the mysterious and haunting nature of the work.
- Mass Effect: The Reapers. We know they reproduce by liquefying various races and then converting that liquid into a new Reaper, but they still look and sound entirely mechanical. This ambiguity is to be expected though, as they are basically Mecha-Cthulhu.
- Half-Life: Pretty much all the Synths used by the Combine. Especially the Strider, which looks like a giant insect, moves around very fluidly, has internal organs (shown when Dog rips out one's brain), and appears to shriek in pain when it dies.
- Final Fantasy XIII: This is pretty much the dominant design aesthetic. We know that the military 'militarizes' wild animals, making them more robotic, but it's unclear how far this process extends. And the wild animals often have a somewhat robotic appearance to begin with, and the 'robots' that don't have wild counterparts generally still have animalistic designs.
- Not to mention the fal'Cie, who look like impossible creatures of living stone and metal.
- Mega Man Legends: The "carbons". The best anyone has been able to tell, they're robots that reproduce sexually or something.
- There used to be a species of humans of ambiguous mechanical-biological ratio in Mega Man ZX, after they combined into one species with Reploids (they were called "humans" for short, as far as we can tell in the Legends backstory), but those went extinct long ago, leaving behind artificial creations and several superpowered killer robots designed to wipe out all the Carbons periodically to keep them at a low level of development and presumably to make them better servants for the now-extinct human-reploid hybrids.
- The Geckos in Metal Gear Solid 4: Guns of the Patriots appear to be giant organic legs with an AT-ST head on top. They bellow like cattle when entering combat and spew black fluid when "killed".
- Goes back a little further to MGS2. The automated Metal Gear RAYs in the Arsenal Gear actually bleed out red "lubrication fluid" when shot.
- To a certain extent, Meta Ridley from Metroid Prime also qualifies, as there's nothing to indicate how much of him is still living and how much is robotic.
- Cyrax, Sektor, and Cyborg Smoke from Mortal Kombat.
- The Starmen in EarthBound. The debates over whether they're robots or aliens in space suits have been going on forever. The actual in-game mechanics make no difference, sudden guts pills and refuels both work on robots and humans alike.
- Most of the paintings of H. R. Giger (who designed the Xenomorphs mentioned on the "Alien" entry above]] fall into this category. Much of his work depicts organic (frequently human) life and machinery intermingling to a point where it's difficult to tell where flesh ends and metal begins.
- Some possible examples exist if you take into account the "perhaps move in a fashion too animalistic to be considered robotic." clause of this article. FESTO produces beautiful aquatic creatures that either float in the air or swim through the water with incredible grace. The Aqua Ray and Aqua Penguins in particular are very lifelike, and look leathery on their skin as they swim. Most people at first glance would think they are actual animals.
- On the opposite side of graceful vs horrible life-likeness is BigDog by Boston Dynamics. The movement of the legs is the most eerie part, it looks as if it had four human legs with the knees facing each other, and it buzzes like a whole hive full of bees. The video in which it gets kicked on a side and tries to remain balanced combines all the evils of Creating Life with literally kicking the dog-deer-hideous-cyborg-creature. If there are comic book villians in Real Life count the guys who manufactured this ambiguous robot in. Also, it's for science of course!!
- Starmen can use pills on other robots, and Poo's "mirror" ability allows him to copy an Atomic Power Robot and refuel allies.