Agent Kallus

"Next time they make a move we'll be waiting for them, to snuff out that spark before it catches fire."

- Agent Kallus' determination to catch the Rebels. Agent Kallus (codenamed ISB-021) is the secondary antagonist of the first and second season of Star Wars Rebels, later a secret ally in Season Three. He is an Imperial agent of the Imperial Security Bureau, assigned in making sure that everyone remains loyal to the Empire and anyone who shows any whiff of disloyalty is eliminated.

His primary objective is to hunt Rebels, investigate any sort of incidents that could spark a Rebellion again the Empire. He is also skilled in actual combat and rather than leading an attack from afar, he involves himself in the field.

After being stuck on one of Geonosis's moons with Garazeb Orrelios, Kallus started out from the empire, he eventually became a Fulcrum (Rebel informant).

Personality
Kallus, like all ISB agents, is devoted to serving the Emperor and protecting his New Order from rebellion at all costs. He has a strong hatred for anyone who opposes the Empire, fueled by his inflated ego and sense of superiority, both of which came from his senior rank. He is ruthless to those who oppose him, and has no qualms with inflicting torture, physical or emotional, showing a sadistic streak when he dueled Zeb. Despite his hatred for the Lothal rebels that constantly escape his grasp, he admits to Grand Moff Tarkin that they have proven themselves "elusive", showing some form of respect or at least acknowledging their skills. In Legacy, however, Kallus admits that he does respect the rebels, even though they represent his constant failures. In "Spark of a Rebellion", he also shows a disregard for soldiers under his command, such as when he kicked a stormtrooper on a pole under him to the latter's demise when the trooper had only asked a simple question. He is unfailingly loyal to his superiors, but is bold enough to (subtly) criticize Tarkin after the events of Mustafar by bringing up how Tarkin's failure has caused whispers on Lothal, how the people are beginning to see the Empire as weak and vulnerable. Kallus' single-minded loyalty to the Empire also made him (at least for the most part) unsympathetic even to his own allies, such as when he expressed little to no remorse over his role in Maketh Tua's death, and appeared to take a sadistic pleasure in her fear of Tarkin and later Darth Vader.

Deep under his tough persona, however, Kallus is not as cold and cruel as he appears to be, and occasionally shows a more vulnerable side. Before the crew of the Ghost detonated explosive paint in the lower hangar of his personal Star Destroyer, the Lawbringer, he instructed his troops to take cover. Additionally, upon confirming that a Rodian civilian was not Tseebo, he told him to enjoy the Empire Day celebrations in an almost friendly tone. Despite his somewhat uncaring demeanor towards the storm troopers under his command, he was visibly shocked by the sudden and brutal execution of Commandant Aresko and Taskmaster Grint at the command of Grand Moff Tarkin. Kallus also displayed a particularly vulnerable side when he was forced to cooperate with Zeb in order to survive, regretfully revealing his first unpleasant encounter with a Lasat and expressing a degree of remorse over the fact that genocide was used to conquer Lasan.

Equipment
Agent Kallus dresses in a standard ISB uniform protected by a heavy black armored vest and helmet. His primary weapon is a modified Lasat Bo-Rifle, which was given to him as a gift from a Lasan Honor Guard he bested in single combat during the fall of the Lasan.

Season One
When the Rebel's heist of Imperial crates caught attention to the Empire on Lothal, Agent Kallus was brought in to investigate. Kallus wasn't so surprised by all this, noting that he was aware of familiar rebel attacks. Considering these ongoing attacks could signify the spark of a rebellion, he was determined to hunt down those rebels and put an end to their rebellion before it could get a chance to spread.

Kallus set up a trap for the Rebels to board an Imperial Transport ship in an attempt to rescue Wookiee prisoners, Kallus and his Star Destroyer came out of nowhere and tractor beamed the two ships to the hanger. However Kallus and his men failed to capture the Rebels but he was able to capture Ezra Bridger and planned to use him as bait, even though Ezra told him he doubted they would come back for him but eventually they did and got away after rescuing Ezra. Kallus and his men showed up on Kessel where they cornered the Rebels trying to rescue their Wookiee prisoners. It was here, Kallus learned of Kanan Jarrus's Jedi identity. He went after Ezra who went to rescue a young Wookiee from a Stormtrooper. Again he lost Ezra and the Rebels but lived to inform The Grand Inquisitor of his findings.

Following a theft of illegal T7 Ion Disruptors committed by the Rebels, Kallus was contacted by Minister Maketh Tua about the incident. Thanks to C-3PO, he was able to find the Rebels location, and led an attack on them. He challenged Zeb to a bo-rifle duel, and admitted he was responsible for the usage of the Disruptors against Zeb's people. He quickly overpowered Zeb, and just before he could kill him, Ezra's Force pushed him away from Zeb.

Weeks later, a cadet named Dev Morgan did some work in his office. The next day, another cadet named Zare Leonis came up to him claiming to be delivering Podracer parts he ordered, to his confusion. Kallus discovered much later that Dev Morgan was really Ezra and that Leonis's delivery was a ruse to help him steal a decoder the Ghost Cell needed to attack a kyber crystal shipment.

At the time of the Empire's fifteenth anniversary, Agent Kallus was involved in the search for a Rodian named Tseebo, a member of the Imperial Information Office, who accidentally downloaded half of the Empire's secrets into his cybernetic implants while searching for information on what happened to Ezra's parents. When the Rebels tried to smuggle Tseebo off Lothal, Kallus pursued them but his attempts to capture the Rodian failed after they escaped aboard the Ghost. However The Grand Inquisitor continued the pursue, leading a squadron of TIE Fighters but ultimately failed as well.

Sometime afterwards, Lothal was visited by Grand Moff Tarkin, who was furious for the Planetary government's ongoing failure to deal with the Rebels and who proceeded to berate Kallus and Tua for allowing the cell to attack Imperial Stormtroopers, destroy Imperial property, and disrupt the Empire's trade. Kallus admitted he'd exhausted every resource to capture them, even bringing in The Grand Inquisitor himself, but the Rebels have proven elusive. The next day, Kallus and Tua looked on in horror as Tarkin had the Grand Inquisitor execute Commandant Aresko and Taskmaster Grint to serve as a grim warning that failure would have merciless consequences from now on. Tarkin then ordered Kallus to dispatch probe droids to find the Rebels. Thanks to the probes, Kallus found the Rebels and he and the Grand Inquisitor succeeded in capturing Kanan Jarrus.

Season Two
Following the rescue of Kanan Jarrus over Mustafar and the death of the Grand Inquisitor, Kallus informed Tarkin that people were beginning to see the Empire as weak and vulnerable. However, Tarkin assured him there was no need to worry as the Emperor had sent an alternative solution to deal with the Rebels: Darth Vader.

Agent Kallus quickly proved himself to be an admirer of the Sith Lord for his creativity, strategic ability, and obvious war experience. When Tua and Kallus were arguing about more methods to find the Rebels Vader came in and told them they were going to do things his way and told Tua that she was to visit Governor Tarkin to account for her failures. Later, Kallus had a probe follow Tua and discovered that she was attempting to defect to the Rebellion. He later escorted her to her shuttle on Lord Vader's orders. When the Rebels attacked and Tua got on the shuttle, Kallus blew it up and framed the Rebels for her murder. Afterwards, he burned Tarkintown and took the inhabitants captive on Vader's orders. When Admiral Konstantine reported that the Rebels got through the blockade and Vader ordered his ship prepared, Kallus informed the Admiral that the shuttle the Rebels stole had a homing device planted on it and Vader planned to follow them back to their command ship. Kallus later congratulated Vader for his victory.

Soon after the Siege of Lothal, Agent Kallus was at somepoint promoted to Commander and was tasked with helping Admiral Kassius Konstantine to locate the Rebels. During that search, they received secret word from Commander Wolffe, a former Clone Trooper, that he and his fellow clones were visited by Rebels Kanan Jarrus, Ezra Bridger, Sabine Wren, and Garazeb Orrelios. He sent a probe droid to investigate, and once it was confirmed he ordered his ship to set course for Seelos. Upon arrival, the Clones refused to surrender their new allies to him. So Kallus went down to the surface with three AT-ATs to commence a ground assault on the Rebels and the Clones. Outwitted, Kallus lost two walkers in battle and was forced to retreat on a speeder bike.

Following his defeat, Agent Kallus and Admiral Konstantine were joined by another Inquisitor sent by Darth Vader, known as the Fifth Brother. Unlike the Grand Inquisitor, This Inquisitor was not highly regarded by Kallus due to his reliance on hunches. When an officer reported a power surge from an abandoned Republic medical station, he dismissed it as something that could be anything until the Fifth Brother stated it was the Rebels and set off alone to nab them himself. He later came back with the Seventh Sister, who Kallus had more respect for.

Sometime afterwards, Kallus was placed in command of the Blockade over Ibaar. When the Rebel Network fleet tried to deliver food to the people, the Imperial fleet easily beat them back. When they came back with the B-Wing, Kallus dismissed the ship as no threat. This complacency would prove to be the blockade's undoing because the B-Wing was powerful enough to enable the Rebels to break through.

When Admiral Brom Titus captured Jun Sato and Ezra Bridger, Kallus told him he was on the way and warned him not to underestimate Ezra. When he arrived, he instantly realized that Titus did not heed his warning to his cost. When the Seventh Sister and Fifth Brother discovered that the Rebel Network was on Garel, Kallus confirmed it and proposed a joint effort. While it ultimately failed to capture the Rebels it did ultimately leave them with nowhere to hide for a year. On Geonosis, it was revealed that his hatred of Lasats, as well as Rebels was due to an unpleasant encounter with a rebel cell led by a Lasat mercenary, which brutally slaughtered his entire unit with Kallus as the only survivor.

Season Three
Six months after the deaths of the Fifth Brother and Seventh Sister, Agent Kallus and Admiral Konstantine have resumed the hunt for the Rebel Network.

They were joined by Grand Moff Tarkin, Arihnda Pryce, the Imperial Governor of the Lothal System, and Grand Admiral Thrawn, the Commander of the Seventh Imperial Fleet. Tarkin informs Kallus of Pryce's theory that the Rebel Network was becoming a growing threat to the Empire. While Konstantine disagreed with her assessment Thrawn agreed and vowed to make the Rebels the architects of their own destruction. Later, they receive a call from Commander Brom Titus telling them the Rebels are doing what Thrawn predicted: Attacking Recrahm Base to steal Y-Wings. When they inform Thrawn, he tells them to let the Rebels go.

In "The Antilles Extraction", he & Governor Pryce arrive at a Tie Fighter Pilot Academy, with information about some Cadets who wish to defect to the Rebels. While his investigation doesn’ turn any thing up, Governor Pryce arranges a Trap, to catch the Rebels in their ranks. While the Rebels are escaping, Kallus appears before them, opening the locked blast door and advising them which floors to avoid, and which hanger to take a Ship from. When Sabine questions why they should trust him, he asks her to tell Zeb that; "(They’re) Even". This allows the defectors to make it safely to the Rebels.

In "An Inside Man", It is revealed that due to his respect for Zeb, Agent Kallus has secretly defected to the Rebellion, taking up the moniker of Fulcrum that Ahsoka once carried. During their return to Lothal, he aids Ezra and Kanan in acquiring information on the new TIE Defender starfighters that Grand Admiral Thrawn has been building, and then makes it appear as though he was thwarted and subdued while trying to stop them. Kallus then meets with Thrawn and Governor Pryce, who believe that there might be a mole within the Imperial ranks. When Thrawn believes that they will succeed in ferreting out said mole, Kallus, in keeping up his act, agrees with the Grand Admiral, saying that his plans always succeed.

In "Through Imperial Eyes", Kallus learns from Ezra that the Imperial Government is on to him. He learns that Ezra is right when he meets his old teacher Corlnel Yularen and Thrawn reveals that he knows about Fulcrum. Believing he can do more good for the Rebellion by remaining where he is, Kallus decides to frame Yogar Lyste for being Fulcrum. He accomplishes this by taking advantage of the ambitous lutenient's woeful naivety and inexperience to trick him into attacking Governor Pryce. His plan works unaware that Thrawn have seen through his trick.

Trivia

 * Kallus's animation model is slightly updated in the second season, featuring a different rank and color to denote a promotion.
 * Agent Kallus is the only remaining antagonist from the first season of Star Wars Rebels.
 * Kallus is one of, if not the only main antagonist in the show to change sides.