A Vulcan of the 21st and 22nd centuries, great-grandfather of Spock, remembered as his world's first ambassador to Earth and named in the lineage Sarek recites on Mount Seleya.
Solkar was a Vulcan diplomat and the founder, so far as the record shows, of the family that produced Skon, Sarek and Spock. After first contact in 2063 he became the first Vulcan ambassador to Earth, beginning the long and often overbearing Vulcan supervision of humanity's progress into space.
His name is first heard in Star Trek III: The Search for Spock, where Sarek identifies himself to the priestess T'Lar as child of Skon, child of Solkar. The diplomatic post is established in Enterprise, in the episode The Catwalk, in conversation while the crew shelter from a storm inside a warp nacelle.
Solkar is never seen on screen, and the link between the ambassador and Spock's ancestor rests on the shared name.