Marta was a female Orion who lived as an inmate at the Federation asylum on Elba II. She was delusional, and seductive. Marta served as somewhat of a consort to Garth of Izar during his attempted take-over of the colony in 2268.
Marta suffered from several delusions, including quoting famous works of literature and claiming that she had written them. In response to quoting William Shakespeare, Garth of Izar called Marta "the greatest liar I have ever met". Marta responded that the fact William Shakespeare wrote the play she quoted did not change the fact that she had written the play again the day before.
After James T. Kirk and Spock were captured by Garth, he placed Marta and Kirk alone together in a room where she tried to seduce him. She was unsuccessful and tried to stab Kirk, who managed to fight her off.
Marta later died on the planet's toxic surface when Garth used her as an example of what would happen to the hostages if he was not allowed to leave the colony. He showed her mercy by blowing her up while demonstrating a new explosive, instead of letting her choke to death. (TOS: "Whom Gods Destroy")
Marta was played by actress Yvonne Craig.
After claiming to have written a poem that in reality is by Shakespeare, Marta later recites another poem she claims to have written. While this is not pointed out, it is not original either: they are from Last Poems XIX, by A. E. Housman. The exact fragment is "In the midnight of November, when the dead man's fair is nigh. And the danger in the valley, and the anger in the sky.".
In Jerry Sohl's original story, the character was a Klingon female named Mara and had a minor role, but the writers and producers changed her species, and made her character be featured more prominently. The character of Mara was transferred to "Day of the Dove". (These Are the Voyages: TOS Season Three [page number? • edit])