The head was the uppermost part of a humanoid, featuring the face and the forehead as well as the brain, skull, eyes, ears, nose, and mouth.
In 2257, when L'Rell was in danger of being removed from chancellorship, Section 31 synthesized heads resembling Tyler and his infant son; thereby making it appear that L'Rell killed them so that she wouldn't look weak to the other Great Houses that made up the Klingon Empire. (DIS: "Point of Light")
In 2268, Kang announced his intention to have James T. Kirk's head stuffed and hung on the captain's cabin wall, following the Klingon's takeover of the USS Enterprise. (TOS: "Day of the Dove")
Cranial lobes, the enlarged foreheads of species such as the Malcorians, were also part of the head. Dr. Berel once stated to 'Rivas Jakara', Commander William T. Riker in disguise, that "your cranial lobes, for instance seem to be surgical implants". Rivas replied that he had genetic irregularities. (TNG: "First Contact")
Data's head was once left in the past under the city of San Francisco for more than five hundred years. (TNG: "Time's Arrow", "Time's Arrow, Part II")
A large sculpture depicting a face was a wall decoration in the atrium of the Vulcan monastery at P'Jem. (ENT: "The Andorian Incident")