Naga Sadow is a Dark Lord of the Sith of the first Sith Empire, a hybrid of human and Sith-species ancestry from Ziost, and a master of Sith alchemy. He was created by Kevin J. Anderson for Dark Horse's Tales of the Jedi, appearing in the 1996 arc The Golden Age of the Sith.
The war that started with a wrong turn
The premise is one of the better ideas in the whole Legends shelf. Two Republic hyperspace explorers stumble into Sith space entirely by chance. Sadow takes their arrival as the discovery of a target; his rival Ludo Kressh takes it as evidence that the Sith should stay hidden. The Great Hyperspace War follows, and the empire loses it.
Alchemy
Sadow is where the setting's idea of Sith alchemy — Force-worked biology, war beasts grown rather than bred — is established. It is a distinct flavour of dark side power, older and stranger than the lightning-and-choking register the films use, and later Legends writers kept returning to it.
Yavin 4 and the long tail
Defeated, Sadow retreats to the jungle moon Yavin 4 and dies there in exile. Two thousand years later Exar Kun follows his trail to the same moon, which is how a comic set in 5000 BBY ends up load-bearing for a Rebel base in 0 BBY. The connective work is deliberate and it is why Tales of the Jedi still gets read.
Canon status
Star Wars Legends. Neither Sadow nor the Great Hyperspace War exists in current canon.
