This is a Costume Trope (and specifically, a subtrope of Cool Crown) where someone with authority wears a crown or helmet made of (or made to resemble) an animal's horns. Typically the character is a royal, though warlords are fans of this fashion statement too, creating fearsome and garish horned helmets.
This is often an in-universe Invoked Trope, with characters trying to look similar to The Marvelous Deer, a Horned Humanoid or even a Beast Man. Just as often the horned animal in question is associated with authority or rulership by the wearer. As the page pic shows stags are often used, though bulls come a close second and basically any horned animal or mythical beast is fair game.
That said, demon-styled horns are a pretty big clue that the wearer is evil. Often there's an aversion where the horns are used as a sign of cuckoldry, which is traditionally represented by "putting the horns" on a man, or even literally growing horns in some plays.
Compare Horny Vikings.
Not to be confused with a "crown of thorns."
- In Bone, this is subverted. There's a Cosmic Keystone called the Crown of Horns, but it turns out to be neither a crown nor horned.
- In his late 80s/early 90s run of the Demon, Etrigan was one of several characters who fought over the rulership of Hell, symbolized by one of these. Unlike the other examples, it most assuredly was named for the the Crown of Thorns, though similarities end there.
- In the Maleficent fanfic Your Servant, Mistress, Maleficent doesn't have horns, but wears a headdress that resembles horns when Diaval first meets her.
- Barbarella: The Black Queen's crown is a single horn, which rather resembles a rhino's. The crown is likely meant to be a visual innuendo.
- Mola Ram, who leads the Religion of Evil in Indiana Jones and the Temple of Doom, wears one of these. It's made from a cow's skull, which is blasphemous in Hinduism (a religion that reveres cattle), just to hammer home the point that Mola Ram "betrayed Shiva."
- Marvel Cinematic Universe: Loki wears a very ostentatious horned helmet. In Thor, it's both a status and ceremonial symbol, like a crown or coronet, indicating his rank as a Prince of Asgard. In The Avengers (2012), it represents his ambition to seize Earth and preside over it as its God-King. The helmet is absent in Thor: The Dark World because he was disowned by Odin, and therefore Loki has been stripped of his royal title. It returns in the third act of Thor: Ragnarok, after Odin has reclaimed Loki as his son, and Loki has decided to rescue Asgard from Hela's blood-soaked reign—he is once again a Prince of Asgard. Intriguingly, his helmet in this movie is more crown-like than in the past because it doesn't cover the top or the lower part of his head, and thus it's more ornamental than his previous ones, which were more practical for battle.
- Ted wears one in The Boy (2015) when he burns down the hotel with everyone inside. His own father included. It was part of an improvised Devil costume.
- The Chronicles of Prydain novel The Book of Three. The chief villain is the Horned King, who wears a mask made out of a human skull with great antlers rising in cruel curves. He is a warlord who is Arawn's champion and the War Leader of Annuvin.
- The Erlking, the wyldfae lord of goblins from The Dresden Files wears a helmet adorned with a massive brace of antlers.
- In Lammas Night by Katherine Kurtz, the coven's male leader wears a horned crown for rituals, to symbolize the Horned God. Religious authority rather than secular/noble, but close enough.
- In Tad Williams' Memory, Sorrow and Thorn trilogy, the king of the Sitha people used to wear a crown of witchwood in the distant past, which looked like stag's antlers. It also made Ineluki look really creepy in a drawing Simon found of him.
- In A Song of Ice and Fire Renly Baratheon's helmet has golden antlers, referencing the stag that is the sigil of his house. His brother Robert Baratheon's crown also has a stag's horns, which is fitting because he is cuckolded by his wife Cersei Lannister and Joffrey, Myrcella, and Tommen are not actually his children.
- In Game of Thrones, House Baratheon is the royal house at the time the series begins. Baratheon kings tend to wear crowns referencing the stag of their heraldry (except Stannis, who is notably crownless). Examples include Robert, Joffrey (whose crown has stylized stag antlers), Renly (pictured, with his fancy golden crown shaped like antlers, arguably the most striking piece of headwear in the series) and Tommen. Tommen's crown of stylized stag antlers looks virtually identical to his brother's. It may even be Joffrey's, but modified to fit his head. After the death of his eldest brother Robert, Renly declares himself the rightful king, ahead of his "nephew" Joffrey and older brother Stannis. Renly's antler crown is a valuable means to create an image of legitimacy. It was chosen as one of The Coolest Helmets, Hats and Headpieces in Science Fiction and Fantasy by io9.com.
- The ritualistic murder that opens the events of True Detective involves a dead woman posed nude wearing a crown of deer antlers. It appears to be part of some sort of paganistic sacrifice.
- In the classic British series Robin of Sherwood, pagan forest-god Herne the Hunter wears some impressive horns.
- The Crown of Horns in the Forgotten Realms setting. An artifact from the ancient magocracy of Netheril that was enchanted by then-god of death Myrkul, it consists of a silver circlet ringed by four bone horns. A thorough Artifact of Doom, as it holds what's left of Myrkul following his death in the Time of Troubles and tends to drive the wearer to evil (or insane in Laeral Silverhand's case).
- Games Workshop games:
- Orcs and Orks in Warhammer and Warhammer 40,000 respectively often wear the very large horns of various creatures, usually to show that they've killed something even bigger and meaner than themselves. Exaggerated in true orkish fashion by their habit of putting either giant tusks or stamped metal shapes of same on their vehicles... including spacecraft. According to some sources, these "giant teef" serve the same purpose as the Imperial Gellar Field: they prevent daemons from boarding the ship during Warp transit due to some combination of orkish gestalt psychic powers and sheer intimidation. Of course, if daemons actually succeed in boarding, the orks view as a pleasant interruption to their daily life.
- Some Chaos artifacts take this form as well (for much the same reasons as the Orks), along with the usual horned helmets.
- In the Warcraft setting, the Horde's first Warchief, Blackhand the Destroyer, wore an antlered helmet.
- There are a number of head armor pieces adorned with antlers that players can obtain, such as the Headdress of the Verdant Circle.
- The Jagged Crown in The Elder Scrolls V: Skyrim is made from dragons' teeth, which are as large as most animals' horns and serve the same ornamental purpose.
- The Master Crown in Kirby's Return to Dream Land takes on a much more elaborate, twisted antler-like form for the Magolor Soul EX fight.
- The Erlkönig also wears an (Awesome, but Impractical looking) antler crown with his fae armor in Roommates.
- In ancient Mesopotamia, bull horns (sometimes more than two) on a crown were a sign of divinity. So the "god"-kings wore them, at least according to relief sculptures of them. And the lamassu and gods wore them on their helms in visual artwork, as well.
- In formal heraldry, the representation of the crowns belonging to Dukes and Kings carry abstract spikes which are thought to be the last survival of animal horns. (Each crown in heraldry has its own formal, rigidly defined, shape which clearly denotes the arms-holder's rank in the social order — ie, that of a baronet is fairly perfunctory, but that for a Duke is highly ornate). The horned helmets of ancient Celts and Vikings — which today are thought as only ever having had ceremonial rather than practical use — are also thought of as having been marks of the wearer's status, so that only a warlord or high dignitary was entitled to wear horns.
- Also, check out use of horned head-dresses in North American Indian society — it's probably no accident that Sitting Bull wore bison horns in his head-dress. Apache shamans wore ceremonial antlers, for instance.
- Secondary wives of Ancient Egyptian Pharaohs wore circlets adorned with the horned heads of ibex and gazelle, symbolizing their grace and beauty. Great Wives wore a tall crown consisting of a pair of cow's horns cradling a solar disk, and embellished with ostrich plumes and as many ureaii (cobra heads) as could be fitted on. Only the gods know how the poor woman kept all that balanced on her head.