Perez

From Memory Alpha, the free Star Trek reference.

Ensign Perez was a Starfleet security officer assigned to the newly-refit USS Enterprise in 2273.

Perez responded to an intruder alert in Ilia's quarters. During the conversation between Kirk, McCoy and the Ilia probe, Perez inquired what was meant by the term "carbon unit." (Star Trek: The Motion Picture)

Perez was played by Joshua Gallegos and was credited simply as "security officer". The novel Ex Machina refers to this character as Joaquin Perez. Gene Roddenberry's novelization of the film refers to him as "Chavez."