Official concept art from a new Obi-Wan Kenobi video confirms the rumor that Inquisitors will be in the upcoming Disney+ series. The clone troopers executed Emperor Palpatine's Order 66 quite well in Star Wars: Episode III - Revenge of the Sith, bringing a swift end to the Jedi Order that had stood for thousands of years - not even Yoda foresaw their betrayal despite being explicitly warned about it. However, some Jedi survived Order 66 and were subsequently hunted down by Darth Vader and his Inquisitors.
Although they certainly weren't Sith, as the Rule of Two dictated that only two Dark Lords of the Sith could exist at any one point in time, Star Wars' Inquisitors belonged to the Inquisitorious organization in which dark side Force-users worked for Vader and Palpatine to hunt down the remaining Jedi hiding throughout the galaxy following the Great Jedi Purge. Several notable characters came into contact with them, such as Kanan Jarrus, Ezra Bridger, and Ahsoka Tano in the Star Wars Rebels animated series as well as Cal Kestis in the Jedi: Fallen Order video game. Now, they will return in the Obi-Wan Kenobi show on Disney+.
An official sizzle reel for Obi-Wan Kenobi revealed concept art for the upcoming series that included an Inquisitor leading two Imperial stormtroopers on what appears to be Tatooine; this comes as director Deborah Chow specifies "Jedi hunters." This would confirm the rumor that the Obi-Wan Kenobi series will include Inquisitors, presumably one searching for Obi-Wan, whom Vader and the Emperor surely knew was alive post-Revenge of the Sith. The only question remaining is, which Inquisitor is appearing in Obi-Wan Kenobi?
A previous rumor said that Sung Kang is playing the Fifth Brother, a character who fought the Jedi alongside the Seventh Sister and Eighth Brother in Star Wars Rebels. That rumor was partially supported by Kang confirming his character uses a lightsaber in the new series, though he didn't confirm if it was a red or blue one. Despite not being Sith, Inquisitors still use red-bladed lightsabers. Interestingly, though, the Inquisitor who appears in the Obi-Wan concept art doesn't look like the Fifth Brother at all. Instead, it looks more like the Second Sister.
Each Inquisitor had a unique look and sometimes a unique lightsaber, and the same applied to the Second Sister, who fought Cal Kestis in Jedi: Fallen Order. However, Darth Vader executed her approximately five years before the events of the Obi-Wan Kenobi show for failing to complete her mission. Either Obi-Wan's Inquisitor is a new one previously unseen who heavily resembles the Second Sister or the series will include flashbacks to previous points in the Star Wars timeline; if not one of those, then it's also plausible that the concept art doesn't resemble the final design for Obi-Wan Kenobi's Inquisitor.