Martina Zoana Mel Navratilova is a princess of the kingdom of Zoana who appears as a primary antagonist in the anime Slayers NEXT. She initially works with her father, the king, in a scheme to capture Princess Amelia of Saillune as part of a broader plot to conquer the world. This plan is thwarted when Lina Inverse and her companions intervene, and Lina's Dragon Slave spell destroys the Zoana castle, leaving Martina homeless and stripped of her royal status. Swearing revenge, Martina dedicates herself to making Lina's life as difficult as possible, often stalking the group and interfering in their adventures. Despite her determination, she is a largely ineffective sorceress with below-average magical ability, though she possesses a talent for casting curses that are more annoying than genuinely harmful. She also worships an imaginary demon god named Zoamelgustar, a deity she invented herself, and frequently carries a talisman representing it, sometimes speaking to the figure as if it were real by changing her voice and expression.

Martina's personality is cheerful and energetic, yet extremely obsessive. She becomes fixated on any idea or goal that crosses her mind, particularly her vendetta against Lina. She is also highly fickle in romantic matters, quickly developing crushes on various male characters she encounters. Over the course of the series, she falls for Zelgadis, Gourry Gabriev, Xellos, and finally Zangulus, with each infatuation ending in disappointment when the object of her affection does not meet her expectations. Her feelings for Xellos last the longest, but she loses interest upon learning he is a mazoku. She eventually marries Zangulus in a makeshift ceremony, as her kingdom remains in ruins.

Martina serves primarily as a comic foil and a recurring source of minor conflict for Lina and her friends. She is more of a nuisance than a genuine threat, and her attempts at revenge often backfire or are easily brushed aside. Despite her antagonistic role, she undergoes some development over the course of the story. When Hellmaster Phibrizo captures Gourry, Martina genuinely joins Lina's group as an ally to help rescue him. During the final battle, Phibrizo appears to kill her, but in her last moments, she urges Lina to keep fighting and save Gourry, demonstrating a hidden capacity for selflessness. Her character is exclusive to the television series; she does not appear in the original light novels or manga. Her full name is a reference to tennis star Martina Navratilova, and this connection is highlighted in an episode where she participates in a tennis-like game called Brass Rackets. Despite her former royal status, she proves adaptable at taking on various odd jobs, such as selling handmade paper flowers or Zoamelgustar medallions, though she usually loses these jobs quickly due to her obsessive behavior.