Guillermo Masada

Guillermo Masada was a male human in Starfleet in the 23rd century.

As of 2366, Masada held the rank of lieutenant, and served as science officer and second officer of the USS Constellation under Commodore Matt Decker. (novel: The Brave and the Bold)

Masada perished, along with the rest of the Constellation crew, during that ship's encounter with an alien "planet killer" in 2267. (TOS episode: "The Doomsday Machine")