With the blankest of blank expressions on their faces, these mysterious figures have been popping up in the most unlikely of places. With a membrane of skin stretched tightly over their eyes, noses and mouths, the alien-like figures were most recently snapped 'watching' a match perched on Murray Mount at Wimbledon.

The pair sit in on a match, where most of the crowd are too absorbed by the game to notice them

Close inspection of the pictures rules out an alien invasion - small perforations around the eye areas of the masks allow the people beneath to see the world outside. But nobody knows who the faceless figures, who often appear as motionless couples are, or why they are turning up at high profile events. Theories include the possibilities that they are  limelight-seeking pranksters, performance artists or that they are at the centre of a viral marketing campaign for an as-yet unknown product of forthcoming horror film.
 

 Another faceless couple stand in the crowd at the start of Harrods summer sale

 Craning his neck - but he won't see anything with skin stretched over his features

Speculation has even arisen that the masks hide a pair of well-know faces, fed up with being harrassed by the paparazzi. One blogger wrote on the Moue Magazine website: "They probably aren’t just random people off of the street. "If it ends up being a pair of celebrities who have had it with being photographed all of the time and are staging a protest, I vow to support every project they appear on from now on.  "Whatever their purpose, I want to join them. And I have a new Halloween costume for this year."

This faceless figure even has his own driver, fuelling speculation that the man behind the mask may be a celebrity himself

Close-up: Eye holes in the spooky mask allows the wearer to see what is going on around him

Theories include the possibilities that they are limelight-seeking pranksters, performance artists or that they are at the centre of a viral marketing campaign for an as-yet unknown product of forthcoming horror film.

What do you think??

-Dunlop