ZO-E3, also called Zoe, was a droid of feminine programming. She served as the co-pilot aboard the smuggler starship known as the Windfall. Above the planet of Mustafar, she and her captain were taken captive while flying the Windfall. An Imperial interdictor ship pulled them from hyperspace. Darth Vader, a Sith Lord, sought the Windfall's captain because he was a descendant of Lady Corvax. Vader ordered the ship to his fortress. There, Admiral Gable Karius went aboard accompanied by a squad of stormtroopers. The stormtroopers shot ZO-E3, and Karius took her captain into custody. ZO-E3 was imprisoned in a cell adjacent to the Mustafarian named Vylip F'alma, who assisted the two smugglers in their escape. F'alma directed the smugglers to his clan's priestess, who resided in Corvax's sanctum beneath the planet's surface. They conversed with the priestess, but Vader trailed them. When ZO-E3 attempted to explain their escape, Vader used the Force to throw her against a wall. Later, she participated in the battle on Mustafar.
ZO-E3 was originally made for Vader Immortal – Episode I. It was the initial part of Vader Immortal: A Star Wars VR Series, a virtual reality series in three parts produced by ILMxLAB. The actress and comedian Maya Rudolph provided her voice.
The spelling of the droid's designation is inconsistent between the installments of Vader Immortal. "ZOE3" is used in the first episode, but the second and third episodes use "ZO-E3." StarWars.com initially used the designation from Episode I in early promotional content, but later materials, such as the reveal article for Episode III, also use "ZO-E3." In the Star Wars Encyclopedia: The Comprehensive Guide to the Star Wars Galaxy which was released on November 19, 2024, the droid's designation is written as Z0-E3, and it appears to be the only source to use a zero instead of the letter O. As "ZO-E3" is the designation used by the majority of sources, this article considers that to be the correct spelling.
Aaron McBride's initial concept art for ZO-E3 depicted her with leg struts that hovered, inspired by the characters B.O.B. and V.I.N.CENT from the 1979 movie The Black Hole. Her head was inspired by a roller paintbrush, which was taken from earlier concepts for L3-37 from Solo: A Star Wars Story. A later concept art piece, also by McBride, showed ZO-E3 with a similar appearance to her final design, but with the leg struts from earlier versions, some differences in color and design, and "Aurebesh" letters spelling "DGH" on the side of her head.