Ars Dangor was the first person mentioned by Mon Mo Hen and he was one of Palpatine’s main mentors. There’s a long history of the character, but he first appeared in a mainstream manner as confirmed in James Luceno’s novel “Tarkin”. He served on the Governing Council of the Galactic Empire (two members of which are seen above in “Revenge of the Sith”), an agency to which the Imperial Security Bureau (ISB) responded. In fact, all the Moffs, Generals, and Admirals report to the Ruler’s Council and the likes of Dangor, and the Ruler’s Council all have Palpatine’s ears. He also traveled with Director Orson Krennic to Geonosis before the Empire’s genocide on that planet to cover up the construction of the Death Star.
Most importantly, Ars Dangor personally has reached the Emperor’s ears and is the confidant of the supreme ruler of the galaxy. Whatever he sees or reports will be revealed to the Sith lord without hesitation. His presence in Mon Mo Henrich’s apartment at her husband’s dinner party makes her realize that her every move, even at home, is being watched by the highest levels of the family. The empire she was fighting was hard to overthrow. No place is safe.
Dangor first appeared in “Star Wars” as a short story for “Imperial Sourcebook”, an add-on to the West End Role Playing Game “Star Wars”, and he may have been one of the mentors of the West End. Palpatine in a major game, the phallic hat is seen when the Emperor arrives at the second Death Star in “Return of the Jedi”, though that question has never been definitively answered.
https://www.slashfilm.com/1029054/lets-take-a-closer-look-at-palpatines-cronies-mentioned-in-andor-episode-4/ Let’s take a closer look at Palpatine’s bunnies mentioned in episode 4 of Andor