No, it is not an alien skull...
(© Denis Gliksman, Inrap)
ALSACE, FRANCE—In a necropolis containing 38 tombs that were used over a period of more than 4,000 years, archaeologist Philippe Lefranc uncovered the 1,650-year-old remains of a woman whose head had been flattened and deformed during childhood. “The deformation of the skull with the help of bandages (narrow strips of cloth) and small boards is a practice coming from central Asia. It was popularized by the Huns and adopted by many German people,” he said. Such deformed skulls are usually seen in burials containing grave goods associated with the wealthy.
I wrote about this awhile back on my old xanga blog...I linked to South American web articles (e.g. at Palenque) where this was done, but some Canadian west coast Indians also made them flat.
But apparently the Huns also deformed their children's skulls, and so this dead woman's skull was not a congenital abnormality but shaped in childhood.
Painting by Paul Kane, showing a Chinookan child in the process of having its head flattened, and an adult after the process.photo from Wikipedia link