Marda Ro was an Evereni female who existed around 382 BBY and was a member of the Ro family. During that time, she resided on the planet of Dalna as a part of the Path of the Open Hand cult with her relative, Yana Ro. Marda held the cult's leader, the Mother, in high regard and trusted her. Ro possessed a calm, composed, and quiet demeanor.
During the Jedi Order's investigation mission concerning the stolen Rod of Seasons, Marda Ro encountered a Pantoran Jedi named Kevmo Zink. Ro and Zink debated their differing ideologies because of the Path's doctrine of abstaining from the usage of the Force, but Ro developed feelings for him nonetheless. When Zink became a victim of the Leveler, Ro attributed his death to the Jedi, not the Mother, justifying that Zink had been misled into the wrong belief system by the Jedi. Furthermore, she convinced herself that Zink's demise was an act by the Force to achieve equilibrium. Consequently, she committed herself to dismantling the Jedi Order, believing it would improve the galaxy, and she left Dalna with the rest of the Path aboard the Gaze Electric to journey to the sacred moon Jedha. Ro was then given the title "Guide of the Path of the Open Hand." As each day passed, she became increasingly radicalized.
However, the Convocation of the Force on Jedha turned down the Path's request, and the Herald instigated a riot that consumed the Holy City in violence, evolving into the Battle of Jedha. Having led the Path there, Ro was criticized for the devastation she had caused. Nevertheless, she encountered Bokana Koss during the battle, who offered her support and with whom she developed romantic feelings. Seeking to redeem herself after her perceived failure, Ro joined Path member and prospector Radicaz Dobbs and his team, along with Koss, on a mission to the mythical Planet X to acquire more Nameless. While they successfully obtained numerous eggs, they were attacked by guardians known as the Under-Dweller and the protector, and Koss sacrificed himself to halt the latter creature. Attributing his apparent death to the misuse of the Force, as Koss had developed Force-sensitivity, and filled with rage and determination, Ro appeared before a crowd that the Mother had assembled to witness the hatching of the newly acquired Nameless eggs. Ro proclaimed that the Path of the Open Hand would transform into a Path of the Closed Fist to retaliate against and defeat the Jedi, inciting them to engage in combat with Jedi who had arrived on Dalna, resulting in a massive conflict known as the Night of Sorrow.
Following the battle, Ro discovered that the Mother had been deceiving the Path about her supposed visions and had been secretly using the Force herself. Consequently, she murdered the Mother using the Leveler. Marda separated from Yana and embarked on a mission to liberate the Force with a revised strategy. Seated on the flight deck of the Gaze Electric, Marda employed brikal-shell paint to create three jagged lines on her head, thus establishing the Nihil. Over time, she came to view her endeavors as neither religious nor connected to the Force, experiencing profound emptiness as she pursued her new path. She gathered many surviving members of the Path of the Open Hand who had never known the Closed Fist into her operation, encouraging them to conduct raids and seize what they desired. She brought the Leveler with her, caring for the creature and feeding it Jedi. She also initiated a search for more members of her species, hoping to start a family. After locating an Evereni old man known only as "Isren," meaning "old uncle," who imparted much knowledge about their people, she eventually found the Evereni siblings Vika and Velya Faer, welcoming them into her ranks. After a confrontation between Vika and Alirya, Ro's right hand, resulted in both of their deaths, Ro invited Velya, who had developed romantic feelings for her, to become her new right hand, and the two entered a close relationship, intending to build a legacy for the Ro family as her new ultimate goal.
When Marda and Yana were young children, the Ro family was attacked by Genetian townsfolk on their last night on the planet Genetia, after the family was blamed for crop failure. During the attack, Marda Ro's sire fought fiercely for the family's escape, while the cousins' grandparents were killed along with Yana's sire. The rest of the Ro family managed to escape Genetia after Yana's mother and Marda's mother killed a family of Theelins and stole their ship.
After fleeing Genetia, the Ro family endured days of hunger and cold as the ship's life support systems began to fail. Eventually, their ship was towed to Nar Shaddaa by a Hutt Clan trawler, where the Hutts attempted to enslave the family. The Path of the Open Hand intervened and paid for the Ro family's release.
Marda and Yana's mothers decided to leave their daughters to the Path of the Open Hand. While Marda recalled feeling lost and scared upon arriving on Dalna as a child, she believed their mothers wanted the two cousins to stay together. Marda coped with the bloodshed and trauma of their escape from Genetia by assimilating into the Path and learning everything she could about the cult's teachings. For years after their initial arrival on Dalna, Marda and Yana lived as members of the Path, with Marda eventually supervising the Littles of the Path. In Yana's view, Marda's memory of the events leading to their joining the Path was scattered and nonsensical. As she grew up as a devout member of the Path, Marda remembered only the safety, security, and sense of belonging it provided.
Marda eventually established the Nihil pirates. She instructed her granddaughter, Shalla Ro, to not imprison Jedi behind bars, but with pain instead.
Marda eventually passed away, and her story resonated through the following century to her descendant Marchion Ro. As a child, Marchion heard Marda's name "a thousand times". In 229 BBY, Marchion mentally noted he had heard Marda's voice in recent weeks. Subsequently, she began to appear to Marchion as a ghost in various forms: as a young member of the Path of the Open Hand, or as an elderly woman. In 228 BBY, as Marchion investigated the plague known as the blight, Marda's ghost appeared to him at several points.
Marda Ro was a character created for the 2022 young-adult novel The High Republic: Path of Deceit, authored by Tessa Gratton and Justina Ireland for the Star Wars: The High Republic multimedia project. Her initial reveal occurred on the cover of Path of Deceit, accompanied by her concept art on an episode of The High Republic Show, which premiered on April 13, 2022.