Originally discovered in 2008, however just revealed to the public last week, was the portrait under Pablo Picasso's "The Blue Room". [OK, so Picasso has never been a favorite artist of mine, however you cannot deny the intrigue factor of this story!] Evidently, this painting has been thought to be hiding something for some time:
"A conservator noted the odd brushstrokes in a 1954 letter, but it wasn't until the 1990s that an X-ray of the painting first revealed a fuzzy image of something under the picture. It wasn't clear, though, that it was a portrait." - http://news.yahoo.com/ap-exclusive-picasso-painting-reveals-hidden-man-065651732.html
The above prompted scientist and art experts to use infrared imaging on the piece, that revealed a picture. One may wonder why this was painted over, which most people are concluding is a result of: a poor - starving artist. Picasso could not afford new canvases as often as he thought of things to create, resulting in his re-use of canvases and even using cardboard for some pieces. [Suddenly I feel better about being thrifty with my art supplies.] Evidently, this comes as no surprise to art experts, the same was demonstrated in Picasso's piece "Woman Ironing" which revealed a the mustached man beneath.
So, who is this guy? Some speculate it is the Paris art dealer Ambroise Vollard, who hosted Picasso's first show. Others, that is could be a self portrait. But no clues were left by the artist to indicate an exact identity. So it remains a mystery!