Green’s Dictionary of Slang

bonehead n.2

[the head is shaved to the bone]

a bald person.

[Aus]R. Park Poor Man’s Orange 75: He said I was a pimply-faced runt, too, the big bonehead.
[UK]Indep. Rev. 18 Dec. 10: Frightening-looking boneheads scowl from the jacket.