Spoiler Warning: This article contains spoilers for The Book Of Boba Fett.
The Book of Boba Fett reintroduced the character of 8-D8, who started off torturing other droids in the dungeon of Jabba's palace in Return of the Jedi. 8-D8 is just one of many evil droids in the Star Wars universe, proving that morality is something that can be programmed — or erased — into machines in a galaxy far, far away.
The evilest droids in the Star Wars universe come from many different sources, including movies, TV shows, as well as books and comics. Some of the worst can be found in Jabba's dungeon on Tatooine, but other evil droids also work for the Empire, the First Order, or on their own as bounty hunters and assassins like 4-LOM.
8-D8
Fans likely recognize the skeletal droid advising Boba Fett in The Book of Boba Fett as 8-D8. This unique droid was seen in Jabba's dungeon in Return of the Jedi, torturing another droid while C-3PO was being reassigned as Jabba the Hutt's protocol droid.
It takes a certain kind of droid to silently hurt another on a kind of torture rack, but 8-D8 was certainly skilled at it. It's even more unsettling now that he is voiced by actor Matt Berry in the new series. Berry, whom fans have likely seen in other Star Wars movies and TV shows, gives the droid a polite and even erudite demeanor that belies his previous behavior.
EV-9D9
Equally evil in regards to other droids is EV-9D9. EV-9D9 also appeared in Jabba's palace and actually ran the operation in the dungeon. EV-9D9 coldly assigned C-3PO to his new fate and cast uncooperative droids to theirs by employing 8-D8.
EV-9D9 is one of the confirmed survivors of Jabba's sail barge and seems to have undergone a change in personality since that event. The droid was last seen tending the bar in the Mos Eisley cantina, a place droids had previously been barred from entering.
BB-9E
BB-9E is one of the few First Order droids seen in the sequel trilogy but easily the evilest. This black and silver droid was a similar make and model as BB-8, but far less endearing. BB-9E tracked Finn and Rose as they infiltrated the First Order flagship and then gave away their position.
BB-9E could be said to only be doing his duty, but he could have altered the First Order to the presence of the intruders at any time. The droid seems to wait until the last possible moment, letting the heroes cruelly think they've accomplished their goal aboard the ship.
Destroyer Droids
Destroyer droids are among the evilest droids in Star Wars entirely because of how effective they are. While battle droids were generally silly and not very threatening, destroyer droids (also known as "droidekas") were silent killers who demolished their enemies.
The destroyer droids are among the best new characters introduced in The Phantom Menace, instantly effective against two powerful Jedi who had taken down a squad of battle droids. They went on to be the most deadly droids during the Clone Wars.
Commando Droids
BX-series droids, best known to fans as commando droids, are among the most ruthless in the galaxy. These highly advanced droids cut through Republic forces during the Clone Wars, silent and methodical in their brutal attacks on clone troopers.
Commando droids possessed increased tactical ability and knowledge compared to their more basic counterparts, and even cruelly impersonated clone troopers, infiltrating Republic forces and then striking them down from within.
4-LOM
4-LOM is one of the most iconic droids in the Star Wars universe, appearing in one of the best scenes from The Empire Strikes Back. This highly advanced protocol droid is also one of the evilest, cutting one of his bounties in half just because he could.
4-LOM also had zero respect for other bounty hunters, except perhaps for Zuckuss. He worked with Zuckuss to steal a frozen Han Solo from Boba Fett before he could deliver him to Jabba the Hutt in the War of the Bounty Hunters comic book crossover event from 2021.
IG-88
IG-88 may not seem particularly evil from his single appearance in The Empire Strikes Back, as he is just standing there on the bridge of the Executor. But he proves himself as one of the evilest droids in books and comics, killing his creators and engineers after coming online.
IG-88 even went so far as to try and kill Darth Vader. He accepted an assignment from a former aide to Chancellor Palpatine, Sly Moore, to take down Vader. IG-88 succeeded in gaining access to the robotics of Vader's suit, scoring a victory against the Sith Lord.
Mr. Bones
Mr. Bones is an augmented battle droid and one of the most insidious droids in Star Wars. Bones first appeared in the Aftermath trilogy of books by Chuck Wendig. He served as a personal bodyguard and took unusual delight in killing others.
Mr. Bones would sing songs while he killed other people, and though he would eventually join the forces of good in the New Republic, never stopped taking relish in delivering the maximum amount of violence that he could to his enemies.
Dark Troopers
The Dark Troopers proved themselves to be highly dangerous and evil in The Mandalorian. These highly advanced troops captured Grogu, destroyed the Razor Crest, and nearly overran the heroes in the second season finale with their terrifying determination to win.
Dark Troopers simply don't care about the odds against them or obstacles in front of them, as they proved in their fight with Luke Skywalker. Though he cut them down with relative ease, the Dark Troopers never once relented as regular troops might have.
BT-1
BT-1 is an assassin droid with a lust for violence. Comic book fans of Doctor Aphra know he is one of two droids associated with the fortune hunter. BT-1 was specifically designed to be cruel and vindictive, resulting in his violent attacks on enemies with a variety of weapons.
BT-1 is outfitted with a number of armaments, including lasers and rockets. Though Doctor Aphra reprogrammed him, he never lost his cruel streak. Though he takes orders from her now, he maintains a frightening capacity to hurt and kill.
0-0-0
0-0-0 is another evil droid Doctor Aphra discovered in the course of her adventures in the comics. 0-0-0 is equally as cruel as BT-1 and in some cases, more so. The droid was intentionally designed by the secretive Tarkin Initiative to torture others and uses his extreme intelligence to do so.
0-0-0 also encourages the behavior of his droid partner, as he did on Geonosis. There, BT-1 destroyed scores of battle droids with a flame thrower and 0-0-0 laughed maniacally as they burned and died.