Thromba was a female Frigosian who practiced cryptosurgery within the walls of Maz Kanata's pirate castle. She collaborated with Laparo, providing cosmetic alterations to individuals like the felon Ryn Biggleston. The First Order's attack, which obliterated Kanata's castle following the Hosnian system's destruction, also resulted in the ruin of her laboratory.
Approximately thirty years post the Battle of Endor, Thromba, a female Frigosian hailing from Tansyl 5, worked as a cryptosurgeon alongside her Frigosian counterpart, Laparo. They operated from a rented tower inside Maz Kanata's pirate castle on the planet of Takodana, offering cosmetic surgery to those seeking anonymity. When the criminal Ryn Biggleston sought Thromba and Laparo's services after killing her criminal accomplice, BeeLee Amdas, the pair altered Biggleston's appearance to resemble Amdas without her awareness, subsequently pilfering a cache of credits she had concealed nearby. The patient then escaped without payment, but was promptly apprehended when Amdas's altered appearance was recognized.
Thromba and Laparo were later observed in the castle's great hall upon the arrival of Han Solo, a smuggler, accompanied by Rey, a scavenger, Finn, a former stormtrooper, and BB-8, an astromech droid. Shortly after their arrival, many of the castle's inhabitants rushed outside to witness the destruction of the Hosnian system caused by the First Order's Starkiller Base superweapon, after which forces of the First Order attacked and destroyed Kanata's castle, including the cryptosurgeon's laboratory.
Thromba's debut was in "The Face of Evil," a short story penned by Landry Q. Walker as part of Journey to Star Wars: The Force Awakens, a multimedia campaign that preceded the release of the film Star Wars: Episode VII The Force Awakens in 2015. Subsequently, both she and Laparo made appearances as supporting characters in the film, portrayed by Annabelle Davis.