Delia Halvern is an Imperial envoy, one of dozens sent on a 7-year mission to survey the Unknown Regions. She is tasked with acting as the official representative of the Galactic Empire on the occasion that new civilizations are discovered. Most famously, she was the envoy assigned to the New Krypton team.
Her sister, Tessa Halvern, commanded the Organization Star Destroyer Harbinger during Lord Karnage's daring assault on the Earth Jedi Temple. Because Delia was in the Unknown Regions at the time, she had no knowledge of her sister's associations or her actions against the Empire, and wouldn't until years after the fact when she finally returned to known space.
In 12 NE, while stationed aboard the Imperial-class Star Destroyer Seeker, the team Delia was assigned to made contact with New Krypton. In the ensuing meeting on the planet with two of its High Councilors, Delia and her team were imprisoned.