Naga Sadow is described in the somewhat legendary Qel-Droma Epics as an ancient Sith Lord who spearheaded the Sith Empire against the Jedi Order and Empress Teta during the Great Hyperspace War, while also being responsible for the Cron Supernova. It is said that the Massassi of Yavin 4 constructed the Great Temple circa 5000 BBY to honor Sadow (his), in spite of how poorly he treated them. A representation of Sadow was carved into the stone of the Sith Citadel located on the Sith planet Exegol. In 35 ABY, Kylo Ren, the Supreme Leader of the First Order, encountered Darth Sidious, the Dark Lord of the Sith, on Exegol and heard Sadow's voice among the indistinguishable murmurs of several Sith Lords.
By 5000 BBY, Naga Sadow was an active male Sith Lord. The Qel-Droma Epics, a series of poems of questionable historical accuracy, place Sadow's activities thousands of years prior to the time of Jedi Knight Ulic Qel-Droma. According to these Epics, the Sith Empire launched an invasion that initiated the Great Hyperspace War during this era. Empress Teta then allied herself with the Jedi Order and defeated Sadow's forces, scattering them across the galaxy. The Qel-Droma Epics also assert that Naga Sadow was responsible for triggering the Cron Supernova by manipulating stars within the Cron Cluster, which in turn rendered the nearby Jedi retreat planet Ossus desolate and scarred.
It is believed that the Great Temple situated on the moon Yavin 4 was constructed by Massassi warriors under Sadow's direction around 5000 BBY. Despite his mistreatment of them, the Massassi revered Sadow as a god, and the Temple was erected to honor him. Archeologists have suggested that the Great Temple may have served as a massive communications device for contacting other Sith Lords throughout the galaxy.
Naga Sadow was among several Sith Lords whose images were carved into the stone walls of the Sith Citadel on the secluded Sith planet Exegol, which is located in the Unknown Regions. The Sadow escarpment, a location on Exegol, was also named to honor the Sith Lord. In 35 ABY, when Kylo Ren, the Supreme Leader of the First Order and master of the Knights of Ren, journeyed to Exegol to confront Darth Sidious, the Dark Lord of the Sith, he traversed the Sith Citadel and recognized the stone statues of Sadow and other Sith Lords from his studies. He also overheard their incomprehensible whispers.
The new Star Wars canon first mentioned Naga Sadow in the twenty-third issue of the De Agostini magazine Star Wars: Build the Millennium Falcon, which was released around June 10, 2015. The character Naga Sadow originally appeared within the Star Wars Legends continuity in the first issue of the comic series Star Wars: Tales of the Jedi - Dark Lords of the Sith, which was penned by Tom Veitch and Kevin J. Anderson and published on October 4, 1994.