Theros Major existed as a planetary body. In the time of the High Republic Era, Stellan Gios, a Jedi Master, and Indeera Stokes, a Jedi Knight, journeyed to this astronomical location where they partook of some food. Stokes quipped in 231 BBY that she would determine if the pickled cushnip served on Valo—a planet in the Outer Rim that would be the site of the future Republic Fair—was better than their dining experience on Theros Major, after Gios expressed his anticipation for the dish.
The 2021 book The High Republic: The Rising Storm, authored by Cavan Scott, referenced Theros Major as part of Phase I of the Star Wars: The High Republic series of interconnected works.