Deception in animals is the voluntary or involuntary transmission of misinformation by one animal to another, of the same or different species, in a way that misleads the other animal. The psychology scholar Robert Mitchell identifies four levels of deception in animals. At the first level, as with protective mimicry like false eyespots and camouflage, the action or display is inbuilt. At the second level, an animal performs a programmed act of behaviour, as when a prey animal feigns death to avoid being eaten. At the third level, the deceptive behaviour is at least partially learnt, as when a bird puts on a distraction display, feigning injury to lure a predator away from a nest. Fourth level deception involves recognition of the other animal's beliefs, as when a chimpanzee tactically misleads other chimpanzees to prevent their discovering a food source.

Some types of deception in animals are completely involuntary (e.g. disruptive colouration), but others are under voluntary control and may involve an element of learning. Most instances of voluntary deception in animals involve a simple behaviour, such as a cat arching its back and raising its hackles, to make itself appear larger than normal when attacked. There are relatively few examples of animal behaviour which might be attributed to the manipulative type of deception that occurs in humans, i.e. "tactical deception". It has been argued that true deception assumes the deceiver knows that (1) other animals have minds, (2) different animals' minds can believe different things are true (when only one of these is actually true), and (3) it can make another mind believe that something false is actually true. True deception requires the deceiver to have the mental capacity to assess different representations of reality. Animal behaviour scientists are therefore wary of interpreting a single instance of behaviour as true deception, and explain it with simpler mental processes such as learned associations. In contrast, human activities such as military deception are certainly intentional, even when they involve methods such as camouflage which physically parallel camouflage methods used by animals.

Robert Mitchell lists four levels of deception in animals:

All four levels are found in nature, including bacteria and plants, but the third and fourth levels seem to be exclusive to animals.

At the first level, an animal acts because it cannot do otherwise, it is programmed to deceive in a certain way. For example, false eyespots such as butterfly markings that indicate their heads are at the back end of their bodies as an aid to escape.

Mimicry is a resemblance of one species to another which protects one or both species. The resemblance can be in visual appearance, behaviour, sound, and scent. There are many types, which can be combined. Defensive or protective mimicry enables organisms to avoid harmful encounters by appearing to their enemies to be something that they are not. For example, mantis shrimps spread their powerful front limbs to threaten rivals. Newly moulted mantis shrimps frequently deceive competitors in this way, even though their still-soft exoskeletons mean that they could not fight without damaging themselves.

In aggressive mimicry, predators or parasites resemble harmless species, allowing them to approach or to attract prey. Anglerfish have a long filament (the illicium) sprouting from the middle of the head above the eyes and terminating in an irregular growth of flesh (the esca). The esca can be wiggled to resemble a small worm, luring other predators close enough for the anglerfish to devour them. Among fireflies, males are lured toward what seems to be a sexually receptive female, only to be eaten. Photuris females emit flashes that resemble the mating signals of females of the genus Photinus. Male fireflies from several different genera are attracted to these "femmes fatales", as the predatory females can identify the male's species and emit the appropriate signals.

In automimicry, one body part of an animal mimics another. This may help an animal to survive an attack, or help predators to appear innocuous. Examples include the eyespots of moths, butterflies, and fishes. These are large dark markings that help prey escape by causing predators to attack a false target. For example, the gray hairstreak (Strymon melinus) shows a false head at the rear of its wings; it has a better chance of surviving an attack to that non-critical part than an attack to the head.