Sullin was a female non-humanoid who lived in the Delta Quadrant in the 24th century and was a member of the Think Tank. A jellyfish-like coelenterate lifeform, she had to be suspended in a tank of liquid, and she communicated with her fellow group members with the use of a device on their ship that allowed them to communicate telepathically. She was an expert of temporal physics, and was regarded by Kurros as one of the most gifted members of their group.
When encountered by Kathryn Janeway and Seven of Nine, they thought Sullin was being studied by the Think Tank members, but Kurros informed them that she was studying them. According to Kurros, she found them "interesting."
Later, when Seven of Nine rejected their request for her to join the Think Tank, Sullin suggested their best course of action was for them to "let the scenario continue." However, this led to the groups' downfall as their plans to obtain Seven failed and their ship came under attack by the Hazari. (VOY episode: "Think Tank")
- Sullin was never named in the episode, but was named in the Star Trek Customizable Card Game. It is unknown if she survived the attack on her ship by the Hazari.