Ogre

An oni, the ogre-demon of Japanese folklore, shown as a mask.

In its familiar picture, an oni is a huge brute with horns, tusks, wild hair and red or blue skin, often gripping a spiked iron club. Oni are the villains of many Japanese tales, most famously Momotarō, the boy born from a peach who travels to Onigashima, the island of ogres, and defeats them. The club even gave Japanese a proverb, "an oni with an iron club": making the strong even stronger.

The emoji is Japanese because it came from Japanese mobile phones. Carriers there drew their own emoji, and those sets were a major source when Unicode standardised emoji in 2010; 👹 arrived alongside its neighbour 👺. "Ogre" is only one English rendering of oni (鬼); "demon" is another.

What does it mean when someone sends 👹?

Usually a monster act: fake fury, a dare or a spooky mood.

After a friendly challenge, a roast or a jokey grievance, 👹 puts on the mask: "you're done for", "come at me". It also tags anything demonic or monstrous, from horror films to a game's final boss.

Japanese speakers may add a layer: oni also describes someone ruthlessly strict or obsessed with work, so 👹 beside a coach or a deadline can mean a merciless taskmaster. Children's tag is onigokko, where whoever is "it" is the oni, and in early February the emoji simply points to Setsubun.

The risk is a serious message. Beside a real complaint or accusation, a demon mask reads as menace, not softening.