I've heard of Slender Man (who hasn't) but Sirenhead is a new one to me. A creation of artist Trevor Henderson, Sirenhead is a gangly, forty-foot-tall cryptid whose head is a pole with two large speakers attached. Those speakers blare air raid sirens, emergency broadcasts, static, eerie snatches of music, and garbled conversations as Sirenhead lurches around the landscape doing Sirenhead things.
After its appearance a couple years ago, the internet quickly became fascinated by this creepy creature and Sirenhead has made its way into urban legend territory, which led to its appearance in fan art and games. Including, recently, Fallout 4, where Sirenhead has become a part of the Whispering Hills mod, a Silent Hill overhaul.
In the mod, the world of Fallout 4 is constantly enveloped in thick silver fog. Fallout 4's ambient sounds are replaced with those from Silent Hill, and ghouls, monster nurses, and other creeptastic creatures from the Silent Hill horror-verse are waiting to drag you away to the underworld.
Here's a spooky video from YouTuber CallMeArktag where Sirenhead appears for the first time in the fog. Naturally, you hear Sirenhead before you actually see him, which makes him all the more creepy.
Sirenhead cuts a pretty scary figure, and I do love the various klaxons and warbling alarms that emanate from his speakers. I do have to say I find him a bit more effective slowly stalking around in the fog than when he stops to slap a giant insect to death with his enormous hands, or when he runs around swinging his long arms, at which point he looks a bit awkward. Still, I already like him better than Slenderman. I wonder who would win in a fight.