Sontor

Sontor was a male Vulcan in Starfleet in the 23rd century. In 2266, he held the rank of Ensign, and was assigned to the sciences department aboard the USS Constellation. (novel: The Brave and the Bold)

He presumably perished in 2267 during the Constellation's encounter with an ancient "planet killer". (TOS episode: "The Doomsday Machine")