Twilight was the code name for a secret large-scale Imperial operation.
Ferus Olin uncovered evidence of it in 18 BBY after hacking Darth Vader's Imperial code cylinder. One stage of the operation was a top-secret project to use a memory-wiping drug on people. The project was headed by Jenna Zan Arbor. She required a test subject who had undivided loyalty to the Empire. Senator Sano Sauro ordered Imperial Academy headmaster Maggis to find such a cadet. Though Maggis thought of Kestrel, Bog Divinian chose his son Lune for the project.
Ry-Gaul and Trever Flume stopped this part of project by destroying the datapad holding information on the formula, while Zan Arbor was injected with the serum, causing her to lose fifty years of her memory and scientific experience. Darth Vader's rage at her failure caused him to personally kill her.
Vader personally wanted use of the serum to erase the memories of his wife.
However, the main purpose of this operation was to eliminate all leaders of the resistance against the Galactic Empire, in one blow. With the help of Eve Yarrow, all major resistance leaders were ferried to Ferus Olin's secret asteroid base. Vader then went to the base with the help of Toma's homing device and destroyed the asteroid with a superweapon mounted on his Star Destroyer, a prototype for the Death Star superlaser. However, the project failed to kill all of the targets, which helped pave the way for the Alliance to Restore the Republic.
- The Last of the Jedi: Secret Weapon (First mentioned)
- The Last of the Jedi: Against the Empire (Mentioned only)
- The Last of the Jedi: Master of Deception (Mentioned only)
- The Last of the Jedi: Reckoning (First appearance)