Moff Gideon is currently the most prominent Imperial leader in The Mandalorian, responsible for the activities of both the Imperial Security Bureau and the Dark Trooper project. In his glory days, he was responsible for the Night of a Thousand Tears, a purge that killed thousands of Mandalorians on Mandalore and made the rest refugees. Gideon is one of only a few left to command the Imperial Remnant after the destruction of the second Death Star at the Battle of Endor, a position which has afforded him the resources to track Grogu and obtain samples of his blood for mysterious experiments.
Sly and ambitious, Gideon has flourished in the waning days of the Empire because he understands the power of knowledge, and knows that there are certain parts of the galaxy that would welcome Imperial control. His reputation may not be as fearsome as some former members of the Empire, but neither is he known for his compassion.
Makes Gideon Look Like A Womp Rat: Darth Vader
The face of the Empire while its Emperor ruled from the shadows, Darth Vader became the scourge of the galaxy after successfully hunting down the remnants of the Jedi Order. He helped Palpatine subjugate worlds, enslave alien species, and crush the spirits of star systems under his heel.
While he may have seemed like a mystical relic of a bygone age, Vader was a terrifying reminder of the Sith legacy, and the immense power of the dark side. Though he served as the Emperor's right hand, his considerable abilities through the Force made him much more than an Imperial stooge.
Surprisingly Kind: Crix Madine
Before he was known for being a strong General in the Rebel Alliance, Crix Madine held the rank of Commander in the Imperial Army and was the leader of the dreaded Storm Commandos. A decorated officer, he couldn't with a clear conscience continue to support the Imperial military's frequent use of genocide as a means of galactic governance.
With his prodigious knowledge of Imperial strategies, he organized and led covert operations from within the Rebel Alliance, such as the assault on the second Death Star orbiting the sanctuary moon of Endor. His plan led to one of the most crucial and exacting victories the Alliance had over the Empire.
Makes Gideon Look Like A Womp Rat: Grand Moff Tarkin
One of the most famous leaders in Imperial history, Grand Moff Tarkin was unmatched in his lust for power and authority, and was as merciless when dealing with Rebels as he was when dealing with his own subordinates. While he was most definitely responsible for the success of the Death Star as a superweapon, he stole credit for its completion from Orson Krennic, and was known to have been behind the deaths of fellow officers vying for the Emperor's favor.
Besides being praised by the Emperor for destroying Alderaan, a planet sympathetic to the Rebellion, Tarkin was the only Imperial officer who held Darth Vader on a "leash", and commanded the Dark Lord of the Sith with a few simple words.
Surprisingly Kind: Admiral Piett
Admiral Piett had the distinction of being the only Imperial officer to appear in two consecutive Star Wars movies, his character having been asked to survive via fan mail to George Lucas himself. In an interview with Jedi News UK, actor Kenneth Colley explained that rather than portray him like "Adolf Hitler" as director Irvin Kershner wanted in The Empire Strikes Back, he decided to convey some semblance of humanity.
Perhaps it's why fans have continued to like Firmus Piett, who was promoted from first officer to captain of Vader's flagship Executor, to finally Admiral after his own superior officer, Admiral Ozzel, blundered the Hoth assault. He seemed to always represent an Imperial officer as just another human, trying to do their job to the best of their abilities.
Makes Gideon Look Like A Womp Rat: Grand Admiral Thrawn
Cold, calculating, and cultured, Grand Admiral Thrawn had the distinction of not only being a brilliant Imperial officer, but the only non-human serving in the Imperial Fleet. Hand-selected by Emperor Palpatine, the Chiss was a cunning strategist who often used his enemies' philosophies and cultural background against them in battle.
Known for respecting his adversaries, Thrawn was also known for being incredibly cruel. In Star Wars Rebels, he was seen forcing an Imperial machinist to kill themselves for suspected sabotage without proof, simply as a warning to the other engineers.
Surprisingly Kind: Admiral Pellaeon
Gilad Pellaeon made his first appearance in the Star Wars Legends book Heir to the Empire, the first novel in The Thrawn Trilogy by respected Legends author Timothy Zahn, and later was canonized in Star Wars Rebels. He became Grand Admiral Thrawn's right hand man following the disintegration of the Empire after the Battle of Endor.
So named after "Pelleus, an idealistic knight from the King Arthur legend", Pellaeon was an officer with scruples. Not only did he found the Imperial Remnant, but he eventually signed the peace treaty between it and the New Republic, ending the Galactic Civil War once and for all.
Makes Gideon Look Like A Womp Rat: Emperor Palpatine
The leader of the Empire always lurked in the shadows, long before the destruction of the Republic, waiting for the precise moment to facilitate galactic domination. Once a Senator from Naboo, Sheev Palpatine murdered his family to prove his loyalty to the Sith, and after becoming a Dark Lord himself began the machinations for the Clone Wars and the destruction of the Jedi Order.
Not even his most trusted officers knew that Palpatine was truly Darth Sidious, save for his apprentice, Darth Vader. His devotion to the Sith allowed him to cheat death decades after the Empire fell, so that even its next metamorphosis (the First Order) could be his to command.
Surprisingly Kind: Agent Kallus
During the early days of the Rebellion, Agent Aleksandr Kallus faithfully served the Imperial Security Bureau, participating in everything from espionage to genocide. Despite being one of the Empire's greatest operatives, he became disillusioned with its mission after working with Grand Admiral Thrawn.
In Star Wars Rebels Season 3, he was so horrified at the Geonosian extermination that he became a Rebel informant, providing the Alliance to Restore the Republic about a faction of TIE pilots looking to defect (many of whom, like Wedge Antilles, would go on to fly with Luke Skywalker in the Battle of Yavin as part of Rogue Squadron).
Makes Gideon Look Like A Womp Rat: Rae Sloane
Rae Sloane was one of the most accomplished Imperial hopefuls to ever join the Imperial Navy. She went from being a cadet to a captain in ten years, and after the Battle of Endor, became a Grand Admiral on the Ravager, the only remaining Super Star Destroyer left in the fleet.
Sloane had the unenviable task of keeping what remained of the Imperial military in line while churlish bureaucrats greedily plotted on how they would divide what remained of the Empire's coffers. After serving as the public face of the dying Empire, she would go to the Unknown Regions with Brendol Hux, his son Armitage Hux, and a few loyal child soldiers and form the First Order.
Surprisingly Kind: Moff Tiaan Jerjerrod
While receiving relatively little screen time in Return of the Jedi, Moff Jerjerrod made a large impression, mostly for quaking in his boots at the thought of receiving the Emperor for an inspection visit when the second Death Star was nowhere near completion. Ultimate Star Wars and Star Wars: Atlas provide more background into the Moff's life, and how he came to be in charge of the second superweapon.
Jerjerrod went from being a diligent student at an engineering academy to eventually becoming a starship designer. Along with Galen Erso, he helped design the first Death Star, a superweapon he told himself would only be used as a means to posture, hopefully deterring attacks from Rebels without having to actually be used.