Darth Wyyrlok is a Chagrian Sith Lord of the One Sith, lore master and the closest confidant of Darth Krayt, appearing from Legacy #1 (Dark Horse Comics, June 2006). The name passes down a family line; the figure in the comics is the third to hold it.
His function in the series is to run the order's doctrine and, when Krayt's Yuuzhan Vong-sustained body begins to fail, to run the order outright while insisting he is only speaking for his master. Filed under the editorial Legacy of the Force bracket, since Legacy is set roughly 130 years after the Battle of Yavin. Star Wars Legends.
Catalogue entry. This figure has a verified record here rather than a full write-up — the encyclopedia labels its own depth instead of padding it.