Pitcairn was a male Human Starfleet officer who lived during the mid-23rd century. In 2254, he was assigned as an operations division transporter officer aboard the USS Enterprise under Captain Christopher Pike.
That year, Pitcairn and his assistant beamed the initial landing party from the Enterprise to the surface of Talos IV, setting them down unobserved in a canyon to the left of the SS Columbia survivor camp.
After Pike was captured, Pitcairn beamed down subsequent landing parties during the attempt to mount a rescue of the captain.
When the acting captain, Lieutenant Spock, made the choice to leave the orbit of Talos, Pitcairn responded from the engine room that they were not able to switch to rockets, because all system were out... "We've got nothing."
Finally, when Pike was able to negotiate for the release of himself, Una, and Yeoman J.M. Colt, and the Talosians allowed them to return to the Enterprise, Pitcairn, who was once again in the transporter room, notified Spock that power had just been restored to the activated transporter, and there was no way to shut it off, moments before the hostages returned to the ship. (TOS: "The Cage")
A recording of his experience aboard the Enterprise under Captain Pike during the original visit to Talos IV, from thirteen years prior, was transmitted from that planet during Spock's fictional court martial aboard the same ship in 2267. (TOS: "The Menagerie, Part I", "The Menagerie, Part II")
Background information Edit
The part of the transporter chief was played by an uncredited appearance by Clegg Hoyt, but his voice was supplied by Robert C. Johnson.  Director Robert Butler approved of casting Hoyt for the role, commenting in retrospect, "That was a good move, I think, because he always brought a reality to anything he did." (The Star Trek Interview Book, p. 99)
Despite evidence the contrary, several reference guides (including the Star Trek Concordance, Star Trek Compendium, and Star Trek Encyclopedia) all associated the name Pitcairn with Hoyt's role, which was otherwise only ever identified in the script as "Transporter Chief", and with no other known documentation made during either production to support that name.
The name used in the aforementioned reference sources was later retroactively applied to the character after the name was used in the closed captioning of the Star Trek: Discovery episode "If Memory Serves".
While the name "Transporter Chief Pitcairn" appears in numerous reference guides, including the Star Trek Concordance, Star Trek Compendium, and Star Trek Encyclopedia, the character himself was only ever identified in the script and on call sheets as the "Transporter Chief". The probable source of the incorrect naming in those references can be found in the script for "The Menagerie", which named the lead security guard in both episodes as "Security Chief Pitcairn".
This character, as identified as the aforementioned "Transporter Chief Pitcairn" was also featured in the comic book series Star Trek: Early Voyages, where it was stated his full name was Nils Pitcairn (β), while Star Trek II: Biographies gives his name as Clegg Pitcairn, and the novel The Children of Kings gives him the first name Glenn.