Ensign Perez was a male Human Starfleet officer in the 23rd century. As a security officer, he was in the security and services branch of the Operations division. In the mid-2270s, he served aboard the USS Enterprise under the command of Captain James T. Kirk.
He 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)