Summary
Star Warshas quietly erased Darth Plagueis' Sith Master, Darth Tenebrous, from canon. The future ofStar Warslies in the past; specifically, theHigh Republic Era, the golden age of the Jedi and the Republic.The Acolytebrought the tail-end of the High Republic Era into live-action at last, and even introduced two Sith of the time - including Palpatine’s eventual master, Darth Plagueis. But who mentored Darth Plagueis?
InStar WarsLegends, Darth Plagueis was taught by the even more mysterious Sith Lord Darth Tenebrous.Star Warsset up Darth Tenebrousin canon all the way back in 2015, inBuild the Millennium Falcon #44. There, an article on Darth Maul’s Sith Interceptor revealed he was believed to have been the ship’s designer, a nod to his role in Legends:

“Said to be one of the fruits of the creative genius of Raith Sienar, the renowned designer’s involvement in the project was later disputed, andthe ship is thought to have actually been designed by Darth Tenebrous, the Sith Master of Darth Plagueis.”
To my surprise, though, it now seemsStar Warshas walked this back.

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Darth Tenebrous' Name Has Been Quietly Erased
I’d read this issue before, so I expected it all to be so very familiar. I quickly realized the issue had been changed slightly, updated, and in factthe name of Darth Tenebrous has been quietly erased. The paragraph quoted above now simply says, “Said to be one of the fruits of the creative genius of Raith Sienar, the renowned designer’s involvement in the project was later disputed.” It’s unclear why this change was made, but the approach is an interesting one nonetheless, because there’s still room for Darth Tenebrous to be slipped back into canon quite easily.
Why Has Star Wars Erased Darth Tenebrous From Canon Like This?
Surprisingly fewSith Lords have been mentioned in canon, largely because the periods where the Sith were more numerous - before Darth Bane and the Rule of Two - have yet to be explored by Disney. This Darth Tenebrous erasure is certainly eyebrow-raising, butthe edit likely reflects the fact Disney has indeed become interested in the Plagueis timeline. Darth Plagueis himself appeared at theend ofThe Acolyteseason 1, and he’s confirmed to be a major factor in season 2 (should the show be renewed).
Realistically, Lucasfilm probably don’t want to wind up locked in because of a throwaway reference in a random fact-file published nine years ago. Recognizing thatBuild the Millennium Falconis still for sale, the lore-keepers must have asked the publisher DeAgostini to make the change. Darth Tenebrous could still become part ofStar Warscanon again, but for now, the Sith mentor of Darth Plagueis is a mystery once again.

Star Wars
Star Wars is a multimedia franchise that started in 1977 by creator George Lucas. After the release of Star Wars: Episode IV- A New Hope (originally just titled Star Wars), the franchise quickly exploded, spawning multiple sequels, prequels, TV shows, video games, comics, and much more. After Disney acquired the rights to the franchise, they quickly expanded the universe on Disney+, starting with The Mandalorian.