Esteban, Captain J.T.
As cpatain of the science-vessel U.S.S. Grissom, Esteban commanded the survey of the Genesis Planet. Among his crew were Lt. Saavik and David Marcus, Admiral Kirk's son.
A conservative, by-the-book officer, Esteban was killed -- along with the rest of the Grissom crew -- when the ship was destroyed by a Klingon Bird-of-Prey during the investigation.