Lieutenant Charlene Masters was a female Human Starfleet officer in the 23rd century. She served in the sciences division aboard the USS Enterprise in 2267 under the command of Captain James T. Kirk, during the historic five-year mission. She had engineering responsibilities aboard the ship.
That same year, Masters was in charge of re-amplifying the starship's dilithium crystals after a near-collapse of the known universe drained them of power and put the ship at risk. Identical beings from opposite universes each desired the crystals for their own purposes. Anti-Lazarus rendered her unconscious and stole a pair of crystals as part of his plan to prevent his mad opponent, Lazarus, from destroying both of their universes. Later, Lazarus created a fire to force her out of engineering to steal his own dilithium.