Selfies taken a moment apart show a tourist photographing his reflection on arrival at an airport.
The first shows him and his camera, reflected in the black glass surface, but the second reveals an unexpected visitor.
Walking just behind him is a bizarre slender figure with a long head whose presence went unnoticed for years.
“I was sliding through the photos later and noticed the thing”
Reddit user baysoi took the photos using his iPhone 4 outside Brazil’s Recife Airport in 2012.
But it was only later that he spotted the spooky figure behind him in the second selfie.
Some viewers suggested it was an “alien ghost figure” or the nightmarish character, the Slender Man.
Others offered more pragmatic suggestions, claiming it was just a woman passing by, walking through the shot.
But if that’s true, it’s unclear how she appeared on one photo but not the other taken a moment before.
Baysoi wrote: “I sust took a few quick snaps and sent one of them to a Whatsapp group.
“The rest of the images were just sat on my phone for a while until I was sliding through them later and noticed the thing.”
He added: “[Recife] is a cool place. I’ve been there a couple of times since. No creepy images of slender men since though.”