As a trope, it is at least Older Than Feudalism—it goes back to the Greek myth of Orpheus's singing head.
A common variation in medieval lore was the Brazen Head, which could answer any question and make oracular pronouncements. The Brazen Head crops up in the stories surrounding many medieval magicians, including Roger Bacon and Faust.
- Clea has Doctor Strange's head in a brandy barrel in Marvel 1602. As is typical of the trope, being dead means that Strange can now tell our heroes stuff that he couldn't while alive.
- The Invisibles also has Ragged Robin stumble across a group of Conspiracy members who receive orders from the head of John the Baptist. Subverted in that Robin just hears the head talking nonsense, and realizes that the head's speaking in tongues; the only reason the Conspiracy members hear orders is because they've been so thoroughly conditioned to follow orders.
- Marvel Zombies Deadpool has been reduced to a Headpool, who is now the regular Deadpool's sidekick.
- Sandman has Orpheus, Morpheus' son, an oracle and disembodied head.
- In Valhalla, the decapitated but still-living head of Mimir is a recurring side character; he's a bit of a grouch and Odin's eternal chess partner. In most of the stories he tends to win the chess ganes (or is about to), although Odin frequently cheats.
- Bob in The Dresden Files. In the books, Bob is an air spirit bound into a skull, while in the TV series, he is a human ghost who "lives" there and comes out when Harry needs his services...or whenever he feels like it.
- In The Last Unicorn, a skull tells the main characters how to find the Red Bull's lair. This was changed to an entire skeleton for the movie, probably to make for more interesting animation.
- In Terry Pratchett's Soul Music, a talking skull appeared in a minor scene taking place in a wizard's workshop.
- Subverted in Don Quixote, where Don Antonio Moreno tricks Quixote into thinking he has one of these, when really it's just his nephew speaking through a tube that leads into the head.
- Alexander Beliaev's sci-fi novel Professor Dowell's Head is entirely about this.
- Inverted in William Gibson's Neuromancer. The ornate head inside the Tessier-Ashpool complex, to which the password needs to be spoken to allow Neuromancer and Wintermute to merge into the first true AI.
- In the novella The Magic Goes Away, the necromancer Wavyhill has cast immortality spells on himself. However, that backfires when his body is hacked up and all that is left is his skull, which due to his magic, he is trapped in and can talk.
- The Skull of Truth from The Little Shop That Wasn't There Yesterday in Bruce Coville's young adult novel Magic Shop series.
- The NICE in That Hideous Strength by C. S. Lewis have the severed head of an executed criminal attached to a machine that keeps it alive and lets it speak. But it turns out it's not the original owner who's using it...
- In Robert A. Heinlein's Magic, Inc., an African sorcerer consults the shrunken head of his grandfather.
- In Tom Deitz's Soulsmith Trilogy, Ronny Dillon creates a Brazen Head through a combination of mechanics and magic.
- In The Shattered World, Pandrogas has a talking brazen head mounted over his laboratory's door as a security device.
- The villains in John Masefield's The Midnight Folk and The Box of Delights make use of a Brazen Head.
- In the Choose Your Own Adventure book Return to Brookmere, the protagonist has a necklace with a talking amulet in the form of a dragon's head.
- There's a little-known medical horror novel, Heads, in which disembodied heads are kept alive against their will for use as living computers.
- The Brazen Head is mentioned in The Iron Dragon's Daughter.
- Zordon from Power Rangers. He's actually a humanoid being communicating from a pocket dimension Rita stuck him in, but the only time we ever see him outside his prison is in the Non-Serial Movie. When he's released from the prison at the beginning of Turbo, he apparently becomes the floating head projection for real. Unfortunately, this makes it easier for the bad guys to imprison him during Space.
- The "Big Giant Head" from 3rd Rock from the Sun.
- At least until he came to Earth in the form of William Shatner.
- The BGH wasn't really oracular so much as he was the Solomons' boss and therefore a figure of terror for them...until he came to Earth, got drunk on the plane, and decided he liked it here.
- At least until he came to Earth in the form of William Shatner.
- The Face of Boe, a billions-year old head-in-a-jar in Doctor Who.
- Additionally, the head of Dorium technically fits this, although he doesn't exactly have much of the characterization (i.e., he has his head wired to surf the internet, and complains of boredom the instant you remove him from a wifi hot-spot).
- The Celtic god-hero Bran the Blessed (no relation, probably), whose severed head continued to speak after his death and, according to one legend, is still buried under the Tower of London.
- Orpheus from Greek Mythology lost his head to a ravening pack of Maenads, and continued to sing for a while afterwards.
- The Head of Mimir from Norse Mythology. Mimir was originally the guardian of the Well of Knowledge, and supposedly all-knowing - after he got himself decapitated, Odin had his head preserved with special herbs and rune-magic, to serve as his adviser. Unfortunately, he's a bit of a prick and makes Odin pull one of his own eyes out.
- Who appears in Too Human, although functioning through cybernetics rather.
- Also the head of Baphomet, supposedly "worshipped" by the Knights Templar following various satanic rites of sodomy (or sodomitic rites of satanism, either way). Of course, the rumor of Baphomet worship was probably a result of torture-induced "confessions", since the Templars were up against a real kangaroo court. Note the word's Arabic origin, probably intended to make the supposed worship extra-scary. Usually described as the Brazen Head variant of this trope.
- It is theorized that there was probably at least a little truth to this rumor, since the Templars dealt in some degree of non-Church-approved heresy. Since the Church has multiple skulls and mummified heads of saints around as relics (Google St. Lawrence the Librarian as one instance among many), the Templars likely DID have a skull relic in their possession.
- In one strip, Calvin pretends to have one of these in a paper bag for Show and Tell. He uses it as a vehicle for teasing Susie Derkins.
'Head': Soooosie is a Booooger Braaiin!
Calvin: It speaks the truth!
- Tabletop RPG example. In the Call of Cthulhu (tabletop game) supplement The Asylum and Other Tales, the adventure "The Auction" had a magical Brass Head that would animate and answer questions if it were covered with burning blood. It was a trap: it contained a Servitor of the Outer Gods which would try to trick the user into releasing it.
- The Planescape campaign setting features Mimir: 'Living' encyclopaedias that take the form of floating, animate skulls and recite any knowledge they contain on demand. Mimirs are magical constructs and typically not sentient in and by themselves (this varies depending on the creator and the Mimir's intended use, however, and sentient Mimir do exist).
- An artifact of this type from Rifts is called Poor Yorick.
- Hunter: The Vigil gives us the Aegis Kai Doru and their most prized possession, the living head of John the Baptist.
- The announcement for the Second Edition of Ironclaw makes a direct reference to the Brazen Head variant.
- The witches use an apparition of an armed head to tell the future to the titular character of Macbeth
- One of the Monkey Island games has a severed navigator's head that leads you through Hell.
- And we can't mention Monkey Island without mentioning Murray the Mighty Demonic Skull from Curse of Monkey Island
Murray: I'm a powerful demonic force! I'm the harbinger of your doom! And the forces of darkness will applaud me as I stride through the gates of Hell, carrying your head on a pike!
Murray: Alright then, roll! Roll through the gates of hell! Must you take the fun out of everything?
- Possibly unintentional, but I always thought that was one of the best pop culture references ever.
- Postie Pete in RuneScape, a talking skull that delivers letters to NPCs. Also one of the Holiday items was a severed Zombie head that you could hold and talk to.
- 'Avernum had the Xian Skull, a skull that would randomly talk while carried around in the party's inventory.
- Bonehead, one of the most memorable characters in the Quest for Glory series (and that's saying something), was - as his name suggests - a skull of this nature, one of many skulls surrounding the hut of Baba Yaga. One of the few things he doesn't complain about is not having Eye Beams like his boneheaded kinsmen, apparently considering sentience a valid trade-off.
- Subverted in Nox. Talking to a recently-deceased mook's skull results in the skull responding, "I'm dead, I can't hear you."
- Urien's ending in Street Fighter III 3rd Strike has this with Urien looking down at the head of Gill, the series' Big Bad and his older brother.
- Myth The Fallen Lords had a talking, severed head show up in the cutscenes, serving as an adviser to the sorcerer-generals in charge of the war against Balor. Turns out that the head is more interested in sowing chaos and discord among the good guys then actually helping them win. Given the amount of stuff that was based on Celtic lore, he's probably based on the aforementioned Bran.
- In The Elder Scrolls III: Morrowind expansion, Bloodmoon, a guy sends you to find his friend, who's an oracle. The friend, it turns out, is a skull.
- The Brazen Head of the Vault Dweller appears in a humorous Easter Egg in Fallout 2.
- The "Meet the Medic" video of Team Fortress 2 features the decapitated but still-living head of BLU Spy, stuck in RED Medic's refridgerator.
BLU Spy: Kill me.
RED Medic: Later.
- Morte the sentient Mimir from Planescape: Torment (see Tabletop Games), who looks even more skull-like than other Mimir. Mainly, this is because Morte ultimately turns out not to be a Mimir, but a piece of the Pillar of Skulls from the first layer of Hell. Morte doesn't just talk, he snarks and jibes and is pretty much 'alive' in every sense of the world but the purely physical one.
- Futurama is known for having contemporary celebrities appear in the show as preserved in jars and fully animated.
- Tarakudo, the Big Bad of Jackie Chan Adventures season 4 until he gets a body in the season finale.
- Transformers Animated: Megatron spends all of Season 1 as one due to damage sustained in the pilot movie. He gets his body back in the season finale.