Siren Head began with a picture the Canadian artist Trevor Henderson posted to Instagram in August 2018: a body some twelve metres tall and thin as dead timber, carrying two emergency sirens where a head should be, joined by black wire. Its skin is dried to the colour of rusted metal, and it appears mostly in photograph-like images, standing at a distance among trees and utility poles.
The frightening part is not the shape but the sound. Siren Head emits radio static, distress signals, and the voices of people calling for people. Henderson has cited numbers-station lore and Junji Ito among his influences. You hear your name, you walk toward it, and the thing that called is what is waiting.
It spread widely in 2020 through games and videos. Because the moment it copies a voice the caller and the called change places, it sits exactly where the line between sending and receiving is rubbed out.