Star Wars: A New Hope, formerly titled Star Wars: From the Adventures of Luke Skywalker, is a Legends novel ghostwritten by Alan Dean Foster and credited to George Lucas. It adapts the film of the same name, and it was based on the screenplay by Lucas. The novelization was first published on November 12, 1976 by Ballantine Books, prior to the film's 1977 release. A sequel, Splinter of the Mind's Eye, was written by Foster and published in 1978. Star Wars Episode IV: A New Hope was later collecte
It first appeared in Tarkin by the same author. The Darth Plague is novel just mentions why he doesn’t use his first name but but what it is.
Tarkin was 2014, Plagueis was 2012 according to Wookiepedia
Plagueis is pre-continuity reboot and has no first name, Tarkin is post-reboot and has the name.