J.T. Esteban
Captain J.T. Esteban was a Starfleet officer in the 23rd century, and commander of the .

In 2285, the Grissom, under Esteban's command, was assigned scientific study of the newly created Genesis Planet. Traveling aboard the Grissom were Starfleet Lieutenant Saavik, and David Marcus, one of the scientists who had developed the Genesis Device. While in orbit, however, they discovered the photon torpedo in which Captain Spock's body had been ejected from the . In addition, sensors registered an animal lifeform on the surface, something previously thought to be impossible.

A cautious man, Esteban refused to allow Saavik and Marcus to beam the tube aboard, quoting the regulation "nothing shall be beamed aboard until danger of contamination has been eliminated." When they subsequently requested to beam down to the planet's surface to investigate, Esteban was wary, stating that regulations only allowed such an action if the captain felt it was safe. Esteban eventually relented, however, allowing them to beam down, but continuously kept Starfleet advised of the mission's progress. 

Esteban and the entire crew were later killed when the Grissom was destroyed by a Klingon Bird-of-Prey commanded by Kruge, during his attempt to obtain and exploit the Genesis technology.

After Admiral Kirk stole the Enterprise in order to return Doctor McCoy to the Genesis planet, Starfleet attempted to contact Esteban to warn him of the Enterprises approach. Kirk found it unusual that Esteban did not respond, and wondered aloud: "What's the Grissom up to? ...Will she join us, or will she fire on us?" He eventually decided to break radio silence and radioed ahead so as to "send Captain Esteban my compliments." ()

Appendices

Background information 
Captain Esteban was played by Phillip Richard Allen.

In the script of Star Trek III, Esteban was referred to as "late forties, a cautious Starfleet veteran," which suggests that he was born in the late 2230s.

Apocrypha 
The ization of  establishes that Esteban was an old friend of Admiral Kirk.

While the creators of Star Trek III didn't leave any evidence of what Esteban's initials stand for, a non-canon source – the Star Trek: The Next Generation Officer's Manual (released for the FASA role-playing game) – lists a Decker-class destroyer, the USS Jonathan T. Esteban NCC-6005, purportedly named for this character.

External links 
 
 

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Humans
USS Grissom (NCC-638) personnel
Starfleet command personnel
Starfleet captains