This is a Costume Trope 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, Horned Humanoid or even 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."
- 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 it might be close enough
- In Tad Williams's 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.
- Game of Thrones provides the page picture of Renly Baratheon. His family's heraldic animal is a stag, and after the death of his brother the king in suspicious circumstances he declared himself the rightful king (ahead of his nephew and older brother). The antler crown follows that motif and was a valuable means to create an image of legitimacy.
- 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).
- 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 bigger and meaner than themselves.
- Malfurion Stormrage is the chief druid of the Night Elves in Warcraft III, and has a big pair of antlers coming out of his head. His brother, who is half-demon, has demonic horns.
- The Jagged Crown in The Elder Scrolls V: Skyrim looks like it's made of dragon teeth.
- In ancient Mesopotamia, bull horns (sometimes more than 2) 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 for 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 - is also thought of as being a mark of the wearer's status, 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 deer-horns, for instance.
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