Baron Yorn was a Coruscant-born male noble in the era of legends. The story goes that around 100 BBY, Yorn led a group of people to Kalakar Six, which is a moon located in the Dromund system. The baron and his followers were drawn to the dark side presence on the moon, and they constructed a fortress there with the goal of performing various experiments. But, when a supply ship landed, the crew discovered that everyone except Yorn had disappeared; Yorn himself had lost his mind and mutilated himself by removing his eyes and tongue.
In the year 0 BBY, Darth Vader, accompanied by a pair of stormtroopers, journeyed to his old fortress to find the Death Star plans. One of the stormtroopers recounted the legend of Yorn to the other.
The character of Yorn appeared in the comic story called "Resurrection," which was released by Dark Horse Comics as part of the Star Wars Tales comic series, specifically in the ninth issue, on October 10, 2001. Ron Marz was the writer of this comic.