Petra Aberdeen was a female Human and former Starfleet officer who lived during the late 24th century.
Early in her life, she graduated from Starfleet Academy. She then served aboard the USS Victory. After achieving the rank of lieutenant junior grade, Aberdeen left Starfleet, as she believed it to be too militaristic and violent. She then became an archaeologist, and joined the Independent Archaeologists Guild by the 2380s.
In 2381, she ran a recruitment booth on Tulgana IV for her guild. In truth, she had been hired to retrieve the Grand Nagus' staff from the Museum of Antiquities and return it to the Ferengi. During the fair, she also met Ensigns Brad Boimler and Beckett Mariner, who ran the Starfleet booth next to hers. Alongside the other booths, Aberdeen constantly teased the ensigns and when Boimler eventually lost his temper, used the diversion to break into the nearby museum. Aberdeen later contacted Mariner to apologize and gave the other woman an open invitation to join the Guild if she ever got tired with Starfleet. (LD: "Reflections")
Later that year, Mariner joined Aberdeen aboard the Free Spirit following her own resignation from Starfleet due to an unfair punitive transfer to the infamous Starbase 80. Mariner was second-guessing her resignation from Starfleet, however, and Aberdeen later caught her digging up information on their benefactor.
In an attempt to convince her she had made the right decision, Aberdeen showed Mariner an FNN broadcast of another crisis Starfleet had caused and that her former ship, the USS Cerritos, was caught in the middle of – in Mariner's absence, Vice Admiral Les Buenamigo had exploited the circumstances that led to her resignation to commission the Texas-class automated starships for second contact duties in place of the California-class, but faulty artificial intelligence had caused all three vessels of this class to go rogue and attack Douglas Station. Seeing this, a horrified Mariner immediately decided to intervene and shut down Aberdeen's protests that the incident was not their fight by pointing out that the people mattered. Aberdeen agreed to help, but was still unsure how they could contribute without getting themselves killed. By the time the Free Spirit arrived on the scene, the Cerritos had lured the deranged vessels away, and Mariner had found the perfect way the Free Spirit could contribute – rallying the entire remainder of the California-class fleet to aid her former ship, an armada which Mariner and Aberdeen led to the Cerritos and the USS Aledo. (LD: "Trusted Sources", "The Stars At Night")
Later in 2381, Aberdeen and her fellows heard Nick Locarno's announcement of Nova Fleet and exhortation for like-minded crews to join him in the Detrion system. (LD: "Old Friends, New Planets")
Petra was voiced by actress Georgia King.