Lieutenant Mallory was a 23rd century Starfleet security officer assigned to the USS Enterprise under Captain James T. Kirk.
In 2267, Mallory was part of a landing party of nine that surveyed the surface of Gamma Trianguli VI. After observing Vaal's civilization and constructs, the excited Mallory ran to inform his superiors. Mallory was unaware that Spock had discovered volatile explosives in the ground strata, and carelessly stepped on one such outcropping, dying from the blast.
Kirk, who witnessed the death, regretted the needless loss, remembering that he had received help getting into Starfleet Academy from Mallory's father.