Cranial Processing Unit

""Just because you're stupid enough to keep your brain in a vulnerable protrusion doesn't mean I'm stupid enough to design a robot that way.""

- Kevyn, Schlock Mercenary

In the human body, the entirety of the brain is conveniently located inside the head. In the world of fiction, this often applies to humanoid robots as well. On a certain level, this would seem to be logical; after all, it's been designed to resemble a human being, with all its corresponding external parts in the appropriate places. It's not a big leap to assume the same would be true for the corresponding internal parts.

From an engineering standpoint it isn't strictly necessary to do it that way. It would be safer to put them in a more protected spot, like in the heavily armored chest, some random spot in the abdomen, or even completely decentralized and spread throughout the body.

However, there are some reasons why you might want to put important functions in the head (for much the same reason that so many terrestrial creatures evolved that way.) Many of the parts related to sensory input, such as visual or auditory receptors, would logically be built into the head for the sake of having a higher vantage point of view; once you've placed those there, you need to place the core processors near them to ensure maximum-speed reaction times to visual stimuli. How important this is and how hard that constraint becomes, of course, depends on how quickly you need your robot to be able to react.

Regardless of whether or not it makes any sense, it's very common for everything that makes up the "brain" of an autonomous robot to be located entirely within its head. If its head is removed and placed on another body, its mind will remain intact. The head may even be able to function completely independent of the body, like a human Brain In a Jar. Damage to the rest of the body might be entirely irrelevant to their ability to survive, and the only way to "kill" them is through damage to their head.

Sometimes related to Losing Your Head, Easily-Detachable Robot Parts, Computer Equals Monitor, Removing the Head or Destroying the Brain.

Anime & Manga

 * Gundam can't always make up it's mind on whether or not this applies to it's Humongous Mecha. For the vast majority of Mobile Suits, the cockpit is actually located in the torso, but the head usually contains the main sensor. A Mook or Red Shirt who's mecha is decapitated is usually at the very least treated like it's disabled, if not destroyed, but one piloted by a main character or Mauve Shirt is often only slightly inconvenienced.
 * The climax of Mobile Suit Gundam simultaneously averted and invoked this trope with the Gundam and the Zeong, respectively. Amuro kept going in the Gundam without its head, while Char ditched the body of the Zeong to continue attacking using its head.
 * Zeta Gundam's Rick Dias and the Sazabi from Chars Counterattack both featured cockpits in the head unit. And like the Zeong above, Char piloted both models.
 * It's deliberately invoked in G Gundam, whose Mobile Fighters are intentionally designed to shut down when their head is destroyed. This design choice is apparently intended to discourage pilots from aiming for the cockpit of their opponent.
 * Mobile Suit Gundam: The 08th MS Team conspicuously averts this in one episode, where Karen's Gundam is beheaded by the first blow of an ambush, but still manages to destroy its attacker. She did need someone else to tell her where to aim, but only because the cockpit displays had been smashed in addition to the head being knocked off.
 * Deliberately invoked in the logic behind a mobile suit variation in Gundam 00. The Neo-Head is an advanced prototype that is compromised solely of arms, legs and a torso, with all cameras, sensors, and processing units distributed throughout the body or within the centre of the torso. The reasons behind it was that in virtually all cases, a mobile suit having it's head destroyed meant that it was combat inoperable, regardless of the rest of it's operational status.
 * Averted by most incarnations of Astroboy, whose CPU is body-centered, contained in a heart-shaped casing inside his chest, making him perfectly capable of functioning with his head knocked off. A little too well, in fact, as Tezuka never did explain how he's able to find his way around without eyes or ears. Maybe one of those wires that's always sticking out of his neck contains a fiberscope?

Comicbooks
"Ivana: HAHAHAHA! You think I keep my brain inside my head? Come on, Khalid! You're an engineer! Think like one! It's inside the torso surrounded by eight inches of solid diamonsteel!"
 * As noted by Linkara in his review of Strange Adventures, the robot is capable of thinking without its head on, so it obviously has a brain in its body, but it stupidly lacks any sensory equipment (eyes, pressure detectors...).
 * Subverted in Stormwatch: Team Achilles with the thoroughly cybernetically modified villainess Ivana Baiul, who mocks the protagonist for shooting her in the head:


 * Remarkably consistent for Transformers. While there have been a few notable instances of Transformers surviving decapitation (or being slain by the same--it seems to vary depending on who's losing their head that day), Transformers killed via having their heads crushed or shot have died on a fairly reliable basis. This may have something to do with the brain module, a concept referenced in earlier issues of the Marvel comic, but seen and invoked in a more gruesome fashion in Transformers: Last Stand of the Wreckers.
 * Averted with Herman von Klempt's cyborg body in Hellboy: Conqueror Worm. Von Klempt has been a head-in-a-jar in every appearance until now, during his battle with Hellboy it turns out that he still is a head-in-a-jar, housed inside an android replica of his original body and still capable of flying around after the body is disabled.
 * Defied Trope in an issue of Spider-Man, in which Dr. Octopus has unleashed several giant robots on New York. Spidey tells the rest of the Avengers to just go for their legs, as their heads are just for show.
 * Played straight with Death's Head, who can continue to control his body even after being decapitated. In Death's Head II issue #1, he gets "assimilated" by being stabbed in the head.

Films

 * Alien had . After having his head knocked off, they plugged him in, and despite having suffered damage in the process, he was perfectly capable of carrying on a conversation as just a head.
 * In Star Wars Episode 2, C3PO's and a battle droid get their heads switched. They both remain quite functional.
 * There may be some secondary processing going on in the body though, as C-3PO doesn't seem to be in control of the body's actions and even seems to temporarily take on aspects of a military droid.
 * The prequel movies had legions of Battle Droids with brainy heads, although they can sometimes walk around a bit after their heads have been cut off, for "comedic" effect.. MagnaGuards however are an example of a droid that can battle on without a head -- something not common in the movies. It certainly surprises Obi Wan when it first happens. They have backup processors in their chest.
 * R2-D2's brain (an "Intellex IV computer", according to the Expanded Universe) is in his head, but his torso is so full of gadgets, gizmos, and dwarf actors that there's nowhere else for it to go.
 * This is one of the few things the movie of I Robot had in common with the book. Sonny had a second one, symbolic of a heart, in his chest, but it was implied to augment the one in his head, with no evidence that it could function on its own.
 * Kay-Em 14 is used this way after Jason knocks her head off in Friday the 13th (film).
 * The Last Starfighter. When the Beta unit (robot) impersonating Alex takes off its head, the head can continue to talk normally.
 * Terminator, since the Terminators all keep their brains/chips in their head.
 * Averted with the T-1000 series (and similar) Terminators, though, since, their "head" is no more (or less) important than any other same-mass portion of their "body", being all composed of exactly the same material, and seemingly equally capable of sensory input and distributed processing as any other equivalent mass of the same material. When the "head" is damaged, or simply when convenient, any other mass can be dynamically reconfigured to serve as the head; and even that is not strictly necessary for it to continue functioning (except for the fact that it is programmed to try to appear as human as possible at all times).
 * Averted in Robert Mason's Weapon (although not in the horrid film adaptation, Solo): the robot's brain is in its chest, and its head is filled with optics.
 * Justified in Real Steel, as these robots are built to mimic human boxers. As such, the spectators expect being punched in the head to have an effect on the robot's ability to fight.

Literature

 * Isaac Asimov's robot stories. If the position of their positronic brains in their bodies is mentioned, it's usually in their heads. For example, in The Caves of Steel R. Sammy is found with an alpha sprayer pressed against his head: the radiation from it fried his brain.
 * Averted in The Stainless Steel Rat, where it's mentioned after diGriz drops a safe on one that police robots have their brains and their voice units in their midsection, surrounded by extra armour. (He knew that; the point of crushing its head was to disable its radio so it couldn't call for backup.)
 * In one of Harry Harrison's Bill the Galactic Hero novels, Bill travels to a planet populated by two warring factions of Mechanical Lifeforms. One of them gets shot in the head by a Chinger guard. When the guard leaves, the robot stops playing possum and explains that his CPU is actually in his butt.
 * Towards the beginning of a Spider-Man / Iron Man crossover novel (just go with it), Iron Man faces off against an incredibly tough attack robot, and with great effort manages to rip its head off. Then he realizes its processors are actually in its chest, which is much more heavily armored. Oh Crap.
 * Briefly mentioned in the Doctor Who Virgin New Adventures book "Original Sin". The Doctor decapitates a hostile robot, and then muses how fortunate it was that the robot's designer had put the brain in the head.
 * The Wild Cards series has the Ly'bahr, a race of brains in jars who can plug themselves into all manner of different cyborg bodies. When they wear humanoid bodies they carefully avert this trope, burying the fragile meaty brains inside the torso, behind the heaviest armor possible.
 * Averted in David Weber's Off Armageddon Reef, where the protagonist is described as having his/her "brain" "located about where a flesh-and-blood human would have kept his liver".
 * At least most of the androids in Rick Griffin's Argo seem to have their processors in the head.

Live-Action TV

 * An episode of Star Trek: The Next Generation had Data using his body to disrupt an electrical arc, damaging it in the process, after which Riker removed his still functioning head and continued on.
 * 790, the disembodied robotic head in Lexx.
 * Red Dwarf - Kryten even has spare heads which have their own personalities.
 * One of the Red Dwarf novels suggests that the circular display on Kryten's abdomen also houses his memory core. If Kryten routinely swaps heads (implied in the TV series to be "once a month") then it makes sense for his body to house a central memory so each head can keep track of what Kryten's current activities have been, even if each head maintains a subtly different personality and its own memory. This may also explain the changes to his personality when he was rebuilt between series two and three - he has the same central memory core but was otherwise extensively reworked.
 * Unsurprisingly The Sarah Connor Chronicles featured this. Although it's indicated that at least some models have a backup system somewhere. The headless body of one Terminator was able to keep functioning so it could search for its head. It even put a motorcycle helmet on top to cover things up. The helmet in question also contained a severed head.
 * The fact that the body didn't start moving until the head arrived in that time makes it seem like the head was remote controlling the body.
 * Averted with Adam in Buffy the Vampire Slayer. While he clearly has eyes on his head and we don't know for certain where his memory and whatnot are located, at least his power core is located in his chest.
 * Played with in Fringe - the shapeshifters have two brains, one in their head and one in their abdomen. However, they will still die if shot in the head.

Tabletop Games

 * Paranoia adventure Send in the Clones. When the Funbot is shot in the head it loses control, running around and bumping into things.
 * In Warhammer 40000, Necron units are explained as being vulnerable to headshots because their brains are still in there.
 * 'Mech cockpits in BattleTech are in the head 99% of the time. But seeing as most of the torso space is taken up by a large fusion reactor, there's not a lot of room to stick a cockpit in there.
 * Averted in Cyborg Commando: the cyborg's brain is in the chest, while the head houses various sensors. (And a large amount of empty space, for some reason.)

Videogames

 * Justified in Sly Cooper, as Clockwerk was originally organic, replacing his organs one at a time.
 * The Mega Man series (Classic, X, Zero, ZX) loves this trope. If the enemy is immune to damage in the body and doesn't have a weak core, it's best you shoot them in the head in order to destroy them. X3 takes this to an extreme, where the absolutely massive final boss can only be damaged by hitting his extremely tiny head.
 * Averted in the 2010 Alien vs. Predator game, which is oddly enough in the same universe as the Alien example. The combat androids can have their heads completely shot off, and continue to not only function, but attack as well. Presumably, they have sensory devices that are also not on their head.
 * The best way to take down the humaniform robots and the "robot dogs" in Mass Effect 2 is a headshot. The larger robots require a bit more effort, though.
 * In Mass Effect 2, most robots are humanoid. Headshots don't really affect geth, but they do severely damage FENRIR, LOKI and YMIR robots, causing an explosion if the robot was killed with it. If YMIR has his head blown off, he explodes like a Cain's shot.
 * At higher difficulties, YMIR mechs can take over a dozen headshots with a sniper rifle to take down. And that's still easier than shooting them anywhere else.
 * Most robots in the Ratchet and Clank series play this straight, but the soldier robots on Damosel in the second game can function with only legs.
 * Robots in the Fallout series take more damage when they are shot in the head. Except for the military Sentry bot in Fallout 3, who actually takes more damage if shot in the chest. Head shots are still a good idea, though, because all the targeting systems are there and it's armed to the teeth.
 * Possibly the Mechawfuls from Mario & Luigi: Bowser's Inside Story. Those things definitely have whatever controls them inside their heads, to the point the head specifically has to be destroyed separately to stop it regenerating the body.
 * Or just keep hammering them, figuratively and literally.
 * The Wood Golem in Popful Mail is similar to the above example in that destroying the body will merely cause the head to bounce around until the body regenerates; killing the head is the only way to end the fight. Averted in the case of Nuts Cracker, who is either a robot, an animate puppet or something in that vein: his favorite method of distracting his opponents is cutting off his own head while his body makes a getaway. (The head then taunts the unfortunate bounty hunter and then explodes.)
 * In Time Splitters you can headshot all robots except for Sentrybot, who has no head to speak of.
 * KAOS in Donkey Kong Country 3. You have to either jump on its head (first battle) or throw barrels at its head (second battle) to hurt/defeat it. It even changes the design of its head, with its first helmet becoming a flying laser-shooting thing and its final head shooting grenades.
 * Phantasy Star Zero both follows this trope and subverts it a bit: Casts play it straight in most every way, but they also have "sub-memory" which is in their bodies and not their heads. It doesn't seem to be enough to back up their personality, however, even though it can hold such high-priority data as an accent.
 * In Vanquish, headshots kill the robotic enemies much faster.
 * In the Metal Gear series, this usually justified by the fact that the robots are manned and have their cockpits on top. With the unmanned models (Gekko and the Arsenal RAYs), this is played straight. Gekko explicitly have their weak point mounted on the top of their hulls, whereas the RAYs' only real weak point (or at least, the only weak point which actually reduces their HP if attacked) is their face.
 * Metal Arms: Glitch in the System averts this somewhat with robots that can function with only legs remaining. However, they can't attack.
 * Binary Domain features various kinds of robots, both humanoid and otherwise. With the humanoid mechs you can blow off any part of their body to some effect, incuding the head, but this does not render them unable to function, it simply blinds them and they start shooting their allies instead. The non-humanoid ones avert this trope to a varying degree. Some have no heads to speak of while others do have heads that serve as "weak" spots, but even those weak spots are heavily armored as opposed to the rest of their body which is simply invulnerable.

Webcomics

 * Averted in Schlock Mercenary, where it's even commented on how it would be foolish.
 * Also, one organic alien survives a headshot, as his "head" is just a big eye and his brain is actually in his pelvis.
 * Darths and Droids mentioned this recently with reference to how strange it is that C3PO still works when his head is grafted onto a battledroid.
 * Briefly discussed in MS Paint Masterpieces, with Mega Man wondering why robot designers always put the CPUs in the robot brains, concluding that if it were up to him, he'd put the CPU in the robot's butt.
 * In a subversion, it turns out Crash Man's CPU isn't in his head. Oh no, that's reserved for more explosives.
 * In Gunnerkrigg Court this does the trick. At least, if you slam poor tin can hard enough to rip out whatever was connected to its head by cables.
 * In Ctrl+Alt+Del a robot was saved due to his designer placing all vital parts in the head and then removing it.
 * Said robot was an X-Box system; the only vital components in the head were the hard drives containing saved games (and personality).
 * Freefall: Averted with Helix (and possibly other robots). As seen in this strip and the next few following it, removing his head has no effect on his ability to think and communicate.

Web Originals

 * Played straight and then lampshaded in Red vs. Blue. Lopez the robot has his body blown up and spends season 4 onwards as a disembodied head. Later in season 4 Sarge wants to retrieve a secret message that was hidden in his databanks, and Grif asks if the data would actually be in his head and Sarge cites the logic behind this trope.
 * Church is kicked out of his robot body if he's shot in the head, which would sorta count as a kill, except he can hop back in just as quickly.
 * The Mega Man MUSH, unlike the games it's based on, generally averts this trope (except for old bots and, well, depends on the creator), as, for robots in general, their neural nets are, as a rule of thumb, in the chest. The head is just one big sensor node.

Western Animation

 * Bender in Futurama is shown more than once to be able to completely remove his head and continue to function in any way his head normally would. He even once was able to function when nothing was left of him but his eyes. His body is still able to move around with the head, it just can't see.
 * Although that time he was reduced to his eyes was only an update-induced dream.
 * Usually averted in Transformers. It varies by continuity whether or not the head even has anything related to thought or memory in it, but they almost always have their most important part, their Sparks, near where the heart would be on a human or the dead center of their chest. Still, a surefire way to get a Transformer to stay down is to tear the head off. Megatron exploited this in Beast Wars, nearly killing the original Optimus Prime on the Ark. Only removing his spark for safekeeping allowed Optimus to be repaired effectively.
 * Played straight in Transformers Animated however, where the heads are shown to contain the transformer's mind. Something that allows Megatron to survive and that the Headmaster exploits. This despite the fact that, as noted above, the Transformers still clearly keep their sparks in their chests.
 * Averted with the robotic Richard Simmons in The Simpsons.
 * My Life as a Teenage Robot