A Vulcan of the 22nd and 23rd centuries, son of Solkar and father of Ambassador Sarek, who is named in the formal lineage Sarek recites when asking for his son's restoration.
Skon was a Vulcan, the son of Solkar, the father of Sarek and therefore the paternal grandfather of Spock. He is known almost entirely from the ritual form of a Vulcan name, in which a person is identified by parent and grandparent.
The name is spoken in Star Trek III: The Search for Spock. On Mount Seleya, the high priestess T'Lar asks who brings Spock's living body and the katra carried by McCoy, and the ambassador answers that he is Sarek, child of Skon, child of Solkar, before requesting the dangerous fal-tor-pan ritual.
A printed English edition of the teachings of Surak glimpsed in Enterprise credits its translation to a Skon, a production detail usually taken to mean the same man. He is never seen on screen.