This skull was found in Greece, about 40 years ago, possibly in the island of Euboea (there is uncertainty about the area it was found).
The length from nose to the end of horns is 67 cm. The skull's length without the horns is 42 cm. Just for reference, the floor tiles in the pictures have a side of 33cm.
What could this animal be? It does not have to be native to Greece, even though a native animal would be more probable.
Update: The size of the skull points to an animal larger than a goat. It looks more like an antelope, a gazelle, or even a deer. Only deers are native to Greece, however the horns look nothing like deer.
I believe the horns are the key to unlock this mystery.