The head, in various senses, often figurative.
One set of words indicates the front or top part of something: masthead, spearhead, warhead, pithead. Another comprises terms for people, frequently derogatory, of which a few are airhead, blockhead, chucklehead, skinhead, egghead, fathead, slaphead (a bald person), and deadhead (a boring or unenterprising person; in the US also a passenger carried free, or a member of an audience with a free ticket, or a follower of the band The Grateful Dead). A third group contains words indicating a person is addicted to some drug: crackhead, pothead, hophead (a drug addict or, in Australia and New Zealand, a heavy drinker). Some indicate a condition or quality (Godhead, maidenhead), for which the more common suffix is now -hood.