Eustacia Okka was a Shadow University employee, specifically a Mirialan professor of the female persuasion. She and Chelli Lona Aphra formerly attended the University of Bar'leth together. Okka's academic pursuits took her elsewhere after the Shadow University dismissed her, deeming her research on the Rings of Vaale unconvincing. She then became a Doctor and started her own archeological work. Following the Battle of Hoth at some point, she chose to join Aphra's crew in their quest to locate the rings.
While pursuing their doctorates at the University of Bar'leth, Eustacia Okka and the unconventional archaeologist Chelli Lona Aphra were both friends and classmates. Once, when bored in a Sava's lecture, Okka read Lost Legends of the High Republic for her dissertation. She thought Aphra would find it strange, but Aphra told her to care less about others' opinions and kissed her.
Their relationship eventually deteriorated. Okka became a professor at the Shadow University, but shortly after publishing an article in the Shadow University Journal about the supposedly cursed artifact known as the Rings of Vaale, the University expelled Okka. They cited "insufficient credible academic research" as the reason. Following her expulsion, she conducted independent fieldwork with the aid of the droid TA-418 and began carrying a blaster.
During the Imperial Era, Okka was investigating the Ruins of Kolkur when Ronen Tagge's mercenaries, representing the powerful House of Tagge, approached her and demanded she assist them in finding the rings. Soon after, Aphra, her former classmate, along with graduate student Detta Yao, bounty hunter Krrsantan, and smuggler Just Lucky, contacted her regarding the rings. As the mercenaries reappeared, the crew escaped aboard Aphra's ship. Okka was initially reluctant but ultimately agreed to assist Aphra and her companions when Aphra guaranteed her sole credit for the discovery, hoping it would lead to the Shadow University reinstating her credentials.
While traveling to Dianth, the rumored location of the rings, Okka's droid TA-418 played a hologram message from Tagge, who reiterated his desire to collaborate with her, tempting her with his vast resources. As Tagge threatened her with a lack of mercy if she refused, Okka ended the message and accused someone on the ship of being a liar.
The crew ventured into the city of Vaale, where Okka separated from the group and discovered the legendary workshop of the Architects of Vaale. The group descended into the sanctum. While attempting to bypass the blocked door, Okka and Lucky returned to the murals to search for clues. As Yao attempted to open the door, the floor beneath them collapsed, causing Okka, Lucky, and Black Krrsantan to fall.
Domina Tagge tasked Sana Starros with locating Aphra, who had been taken over by the Spark Eternal. To do this, she gathered a team of individuals who knew Aphra well, including Okka, one of Aphra's former partners. They met with Magna Tolvan, who initially regarded the mission and the team with disdain but joined after Starros' passionate appeal. She thought Aphra would have concealed something significant at the scene of a personal triumph, as she enjoyed boasting. They chose to go to Birukay, discovering numerous dead and severely injured Crimson Dawn members. While walking, they noticed a small hut but were attacked by more Crimson Dawn members. Starros instructed Okka to protect Korin Aphra from the fighting. However, upon reaching the hut, they realized it was a trap, and Aphra had left 0-0-0 and BT-1.
Eustacia Okka was a green-skinned being with darker green markings on the left side of her face. She had white hair, dark eyebrows, and purple eyes. Aphra noted during their university years that Okka was overly concerned with how others perceived her and her work.
Alyssa Wong created Eustacia Okka for the 2020 Star Wars: Doctor Aphra comic series. Wong introduced Okka in an interview published on StarWars.com on January 23, 2020. The character made her debut in the series' first issue, written by Wong, illustrated by Marika Cresta, and published by Marvel Comics on May 4, 2020.