Wiliam Theiss Raymond was a Human, and a progeny of Clare Raymond. He was the son of Scott Sendfonte Raymond and Hannah Shearer Raymond. He had a brother named Robert. (TNG: "The Neutral Zone", okudagram)
The name of this character was never mentioned in dialog; the name came from the remastered Clare Raymond family tree. His name was an in-joke referring to costume designer William Ware Theiss.