Darth Krayt, born A'Sharad Hett, is a human Sith Lord and the founder of the One Sith, the order that rules the galaxy in Dark Horse's Star Wars: Legacy (2006–2010) by John Ostrander and Jan Duursema. He first appears as Krayt in Legacy #1 (June 2006), having been introduced years earlier as the Jedi A'Sharad Hett in the Dark Horse Star Wars ongoing.
Tatooine
Hett is the son of a Jedi who left the Order to live among the Tusken Raiders, and he grows up as one of them — a detail that quietly rewires the desert planet the saga started on. He serves as a Jedi through the Clone Wars, survives the purge, and spends the following decades in exile.
Filed under an era that does not fit
Legacy is set around 130 years after the Battle of Yavin, well past the end of any official era label. This site files Krayt and the One Sith under Legacy of the Force, which is an editorial subdivision rather than one of Lucasfilm's nine eras, and says so here so the date is not mistaken for a claim.
The Rule of One
His doctrinal contribution is the inversion of Darth Bane's. Two Sith are too few to hold a galaxy, Krayt argues, and the secrecy that kept them alive also kept them powerless. So he builds an order of many, bound not by a rule of succession but by absolute personal loyalty to him — the Sith reorganised as an army with one commander. It works, which is what makes it interesting; the comic's problem is not defeating the Sith but living under a Sith government that functions.
The Yuuzhan Vong
Krayt's body is kept alive by Yuuzhan Vong biotechnology grafted into him during his capture and torture — the same invaders from the New Jedi Order novels, reaching a century forward. It is a good piece of continuity work: the Legends shelf's biggest crossover event leaves a physical mark on its furthest-future comic.
Cade Skywalker
The series pairs him against Cade Skywalker, a descendant of the family who wants nothing to do with any of it, and the pairing is the whole book: an emperor who believes in his order absolutely, against a bounty hunter who believes in nothing and is the only person who can stop him.
Canon status
Star Wars Legends. Legacy, the One Sith and Krayt were all moved to the Legends shelf in 2014.
Reading note
Start at Legacy #1. The A'Sharad Hett material in the earlier Dark Horse Star Wars run is worth reading afterwards, as background rather than as a prologue.