This skull was discovered in France between 1920 and 1940.
Its easily one of the more disputed and controversial artifacts of its time.
The museum of supernatural history claims (through analysis) that the horns are in fact, naturally a part of the skull.
I thought this was a really cool picture, but the complete and total lack of any kind of sourcing bothered me. Google time!
The very same picture showed up on CultCase:
During an archaeological dig in Sayre, Bradford County, Pennsylvania in the 1880s, a number of human skulls were unearthed. These skeletons were anatomically correct, except for the anomaly of their projections, two inches above the eyebrow, and the fact that their average height in life would have been around seven feet tall. The bones were sent to the American Investigating Museum in Philadelphia, where they were stolen - never to be seen again.
This American Investigating Museum, by the way, has not shown up anywhere at all except in quotes about the skull.
While it’s not unexpected, I always feel just a bit disappointed when something potentially awesome turns out to be fake. D: On the other hand, I think this might spark some story ideas. Can you imagine how awesome something with a skull like that must look fleshed out?