The octopus has many skills that help it catch prey and evade predators. Most species can use camouflage, they can squirt clouds of ink to obscure themselves, and they can squeeze through incredibly tight holes. And, to top it all off, they are incredibly intelligent. These abilities help the octopus make up for what it lacks in tough skin.
Therefore, anthropomorphic octopus characters in fiction are very likely to be portrayed as slippery characters who are masters of espionage. Their camouflage abilities make for a great Master of Disguise. Some may even pretend to be humans.
Other cephalopods, like squid and cuttlefish, can count for this trope too. Cuttlefish are quite notable for camouflage abilities too, but the octopus is perhaps the most well-known cephalopod for having sneaky abilities. Octopoid Aliens can count as well.
The Giant Squid usually won't act stealthy, though, mainly because most fictional portrayals are all brawn and no brains. However, real giant squid actually do lean towards stealth. They may not have camouflage, but they are rather shy and rarely leave the deep sea where it's dark - most of the giant squids observed alive in the wild are either juvenile or elderly squid, both of which are thought to venture to shallower water more often than mature adults.
Subtrope of Animal Stereotypes and Stealth Expert. Compare other cunning animals: Cunning Like a Fox, Rascally Rabbit, Rascally Raccoon, Sneaky Spider (Another eight-legged one!) and Those Wily Coyotes, as well as Hollywood Chameleons for another animal notable for changing colors.
- Parodied in Hard-Boiled Cop and Dolphin, where the first ocean criminal is an octopus man who tries to hide by curling up, even though he can't blend in on an empty street on dry land. It actually ends up working anyway, because Chako plays a game of peak-a-boo with him that distracts Samejima enough for the octopus to sneak up on him between panels.
- Sonic the Hedgehog (IDW): Mimic the Octopus has the uncanny ability to perfectly shapeshift into the form of... pretty much anyone. He uses this talent to work as a master infiltrator and mercenary. His personality reflects this ability - just as he is constantly changing forms, he suffers from Chronic Backstabbing Disorder, frequently deceiving and betraying others for his own benefit.
- The Spirit: Invoked. The Octopus uses the octopus as his namesake, and always hides his appearance with obscuring clothes or by staying just outside the panels.
- In Finding Dory, Hank the "septopus" (an octopus with one tentacle missing; it's unclear if this is a birth defect or his tentacle simply hasn't grown back yet) is good at sneaking around, thanks to his quiet nature and ability to change his skin colour.
- The Little Mermaid: Ursula, the half-octopus sea witch, transforms herself into a beautiful human woman named Vanessa to seduce and hypnotize Prince Eric. However, she does the transformation by magic rather than by any natural cephalopodian abilities, which is what this trope usually implies.
- Penguins of Madagascar: Dave the octopus disguises himself as a human by changing his skin color to a Caucasian skin tone, putting on clothes, a wig, and glasses, and standing up straight. He still looks very different in a Gonky way, but none of the humans notice.
- Galaxy Quest has a more benign example than usual. The Thermians, a race of Octopoid Aliens, disguise themselves as humans when talking to the human protagonists, but they are friendly and are only taking these forms so that the protagonists can understand them.
- Jurassic World: The Indominus rex is able to camouflage herself against the jungle backdrop, with Dr. Wu later saying that this is a direct result of the cuttlefish DNA used to create her.
- It's hard to say what the creatures from Monster Trucks are, exactly, but "cephalopod" seems as good a guess as any (for one thing, they have tentacles). They are certainly sneaky, able to get around quite quickly, squeezing through incredibly narrow gaps and really only struggling on open country. The premise is that they are able to hide in plain sight by squeezing into truck engines.
- In The New Legends Of Monkey, Lady Tsumori is an octopus demon, and her talent is changing her shape to impersonate others in order to sow distrust.
- A very dark example in The Twilight Zone (2019) episode "8." Researchers in an underwater station discover a large, preternaturally intelligent octopus has snuck aboard after possibly killing one of their colleagues. They attempt to study it only for it to escape and wreak havoc, sneaking through the pipes to make another kill and even hacking into the station's computer; By the end, the researchers realize the octopus is part of a newly-evolving species, preparing to adapt to dry land and replace humanity as the dominant lifeform.
- Dungeons & Dragons 5th Edition gives octopuses the ability to make stealth checks with advantage when underwater, reflecting their camouflage abilities, as well as the ability to obscure the area around themselves with ink and double their movement speed in a single turn.
- Dillon's Rolling Western: Nomad, a squid, is known in-universe as "the Assassin" for his skill as a Cold Sniper. He ranks high in speed and swimming skill, but not so much in power or toughness. He also wears a poncho that conceals most of his upper body and face.
- Kirby's Epic Yarn: Capamari, the Giant Squid boss of the water world. After removing his cap to expose him as an octopus, Capamari fills the stage with ink and disappears, with his eyes later fading in as the only visible parts of him. Capamari later tries to hide in one of four jars, although he keeps sticking his head out to look around, making it obvious which jar he's in.
- The Octoroks in The Legend of Zelda are portrayed this way in the 3D games. Ocarina of Time, Majora's Mask, and The Wind Waker have them hide in bodies of water and only pop up to spit rocks at Link. Skyward Sword introduces a terrestrial variant that hides under bushes, while Breath of the Wild has variants that hide under boulders and fake treasure chests.
- Mega Man Zero: The fourth game has one of the bosses, Tech Kraken, a squid-based Reploid who used to be a member of Hidden Phantom's espionage unit. He has a tricky fighting style, with one of his moves having him using his squid ink to obscure himself so he can strike from the dark using his sharpened tentacles.
- A number of characters in the Metal Gear franchise are associated with octopuses, and excel at espionage-related skills:
- Decoy Octopus from Metal Gear Solid is a Master of Disguise and FOXHOUND unit's deception and impersonation specialist. His disguises are so thorough that he even goes so far as to inject blood samples from those he impersonates into his own body.
- In Metal Gear Solid 4: Guns of the Patriots, Snake wear a suit made from a material called OctoCamo, named in honor of the octopus' mimicry ability, that can adopt the appearance and texture of any wall or floor he presses against and providing camouflage that can fool both the naked eye and infrared sensors. The boss Laughing Octopus has an even more advanced version of this suit that can mimic extremely complex objects, such as medical equipment and Snake's Robot Buddy the Metal Gear Mk. II.
- Octodad: Played for Laughs. Octodad is an octopus who pretends to be human just by wearing a suit and standing up, making no attempt to hide his face or tentacles or anything. He would be noticed immediately if people in his world were sane enough, but thankfully, they're not... unless Octodad makes enough mistakes by knocking over or running into things. It is very hard for an octopus to walk like a human, after all.
- Both the Inklings and Octolings from the Splatoon series have the ability to hide in their ink to keep hidden from enemies. The Ninja Squid skill that can be on clothing takes this Up to Eleven as no trail will show when the wearer is hidden.
- Super Bomberman 3: The Deep Sea world has enemies called Sea Balloons. They are red octopi that can hide under the sand to avoid explosions and spit ink that makes the screen darker, thus making it harder for the player to see.
- Sea Fortress 2 is a Gag Dub of a nature documentary where the animals are given the voices of characters from Team Fortress 2. In this video, the mimic octopus, which is known to impersonate other animals for protection, is given the voice of TF2's Spy, a Master of Disguise who relies on stealth, just like the octopus itself.
- The TierZoo video "Optimizing Stealth Builds" describes animals as if they were video game characters, and explains various strategies used by stealth players. Cephalopods are noted to have the highest stealth stat in the game thanks to their ability to change not only their color, but also their shape and texture to match any environment in the ocean.
- Alfred J. Kwak: Lispel seems to be an octopus (he has suckers on his tentacles like an octopus), yet strangely refers to himself as a jellyfish. Either way, he is a freelance spy who will work for anyone who is willing to pay him for his services. It should be noted that the Dutch word for jellyfish, kwal, can also refer to a slimy and untrustworthy person. So even though Lispel looks and behaves like an octopus, the Punny Name was probably too good to pass up. He also uses Sssssnake Talk.
- In the relaunch series of Danger Mouse, Agent 58, the Danger Agency's Master of Disguise, is a mimic octopus. (Based on, and said to be the son of, the original series's Agent 57, whose true form was never revealed.)
- In The Deep episode "The Abyss Stares Back," the deep-sea diving heroes start seeing strange doppelgängers of themselves down in the impossibly deep ocean. They turn out to be vast groups of tiny squid, forming together into shaped swarms and camouflaging themselves to resemble divers, submarines, or whatever.
- The mimic octopus (Thaumoctopus mimicus) imitates other sea creatures, such as lionfish, sea snakes, and more, to hide its identity and convince would-be predators to stay away.
- Inky the Octopus, who escaped from the National Aquarium of New Zealand by breaking out of his tank and slithering down a drainpipe leading to a nearby bay.
- Similarly, there was an aquarium with a tank whose occupants were disappearing. Security cameras eventually saw that it was an octopus from a nearby tank, which would climb out, slither over to the next tank, devour its prey, and return to its own tank.