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"Chancellor, I must protest. Besides being the last of its kind, this creature may be intelligent."
―Sionver Boll, protesting the killing of the Zillo Beast[5]

Sionver Boll was a female Bivall scientist contracted by the Galactic Republic during the Clone Wars. A brilliant inventor and engineer, Boll was the head of her own laboratory that conducted weapons research and development for the Republic war effort. Among the devices created by her lab was the electro-proton bomb, a superweapon that created an electromagnetic pulse that could disable electronic machinery such as battle droids, the main components of the Confederacy of Independent Systems Army. Boll oversaw the first field experimentation of the electro-proton bomb during the Battle of Malastare, but the superweapon had an unintended side effect when it created a massive sinkhole and awakened a dormant Zillo Beast.

Supreme Chancellor Sheev Palpatine tasked Doctor Boll with studying the Zillo Beast for the Republic and had the creature transported to Coruscant. Though she had ethical concerns and objections, Boll complied with orders to kill it, but while attempting to do so, the beast broke from its confinement and rampaged through Galactic City. Working with the Republic Military, Boll quickly developed enough toxic gas to kill the Zillo Beast. After the creature's death, Palpatine ordered Boll to clone it, but her attempts proved unsuccessful, and the project stagnated. After the rise of the Galactic Empire, Boll's research fell into the hands of the Advanced Science Division, which successfully sequenced several clone specimens.


A new superweapon[]

Chancellor Palpatine: "I assure you, Doge Urus, that will not happen. Doctor Boll has stated that only droids will be affected by the bomb's electron field."
Sionver Boll: "Yes. The clones and your people will be quite safe. We have accounted for every probable outcome."
Mace Windu: "It's the improbable that concerns me, Doctor."
―Palpatine, Boll, and Windu discuss the electro-proton bomb[4]

Dr. Sionver Boll and her lab developed the electro-proton bomb for the Galactic Republic.

Sionver Boll hailed from[3] the agriworld[6] Protobranch, the homeworld of the Bivall species[7] located in the Core region of the galaxy.[6] As a Bivall, Boll possessed a high intellect and was predisposed to a career in science.[7] A brilliant scientist,[2] Boll specialized in various fields[5] and would go on to become the head of her own development laboratory. After the onset of the Clone Wars,[3] a pan-galactic conflict between the Galactic Republic and its splinter state, the Confederacy of Independent Systems, in 22 BBY,[8] Boll lent her services to the Republic.[2] Contracted by the Republic Military, Boll devoted the resources of her lab to produce inventions useful to the war effort, with a special focus on military weapons research and development.[3] In this role, Boll experimented with weaponry that would work against battle droids, which comprised most of the Separatist Armies, while leaving organic soldiers such as the Republic's clone troopers unharmed. To this end, she and her lab spearheaded the development of the electro-proton bomb.[4]

As designed by Boll,[4] the electro-proton bomb would create an initial concussive shockwave when detonated, followed by a sphere of ion energy. This electromagnetic pulse would shut down all electronic and droid technology within its radius, rendering Separatist droid combatants useless.[9] By the time Boll's lab had fully realized a prototype of the superweapon[3] in 21 BBY,[8] the Republic was locked in a lengthy and costly battle with a massive Confederate armada on Malastare. At stake was access to Malastare's fuel resources, which the Republic needed to maintain its armed forces. As the campaign devolved into a battle of attrition that seemed certain to end in a Separatist victory, Supreme Chancellor Sheev Palpatine of the Republic authorized using the electro-proton bomb to turn the tides on Malastare swiftly.[9] Doctor Boll accompanied the electro-proton bomb prototype to Malastare, where she planned to oversee her device's inaugural field use.[4]

Electro-proton explosion

The electro-proton bomb, a weapon of Doctor Boll's invention, is deployed on Malastare.

Although Boll promised the bomb would work as intended, it was met with uncertainty from the Jedi Generals leading the Republic forces on Malstare, Mace Windu and Anakin Skywalker. The bomb further put a proposed treaty between the Dug Council and the Republic into question, as its success or failure would influence Doge Nakha Urus's decision. At the Imperial palace on Malastare, Boll met with Windu, Skywalker, and Urus at the Republic's command center, where they were joined by Chancellor Palpatine via hologram. From her vantage point in the palace, Boll watched as Separatist forces advanced on the plains surrounding the palace and the Republic troops who created a front to keep them at bay. As they waited for the assault to commence, Boll and Palpatine assured Doge Urus that the electro-proton bomb would not harm the Republic clones nor the Dug cavalry. Boll remarked that she had taken all probable outcomes into account to ensure the bomb's effectiveness.[4]

General Windu interjected that he was concerned with the improbable, adding that there should be other options besides deploying a superweapon. Palpatine disagreed, expressing confidence in Boll's weapon, and stated that the bomb was the only sure way to emerge victorious. Looking at the Confederate armies gathered across the plains, Skywalker announced they had begun their assault. With the Republic and Confederate forces engaged in combat, Skywalker called in the Y-wing squadron handling the prototype and ordered them to drop the bomb. Though it faced heavy fire, the Y-wing reached the drop zone and dropped the bomb on the Separatist army. Boll watched the prototype explode as intended, with the electromagnetic pulse enveloping the battlefield and deactivating all electronics. Skywalker warned that the ion pulse was approaching the palace, and Boll and the others braced for impact. The pulse quickly phased through the palace, leaving Boll unscathed, although contact with Palpatine was lost.[4]


Doctor Boll and Chancellor Palpatine are shown the Zillo Beast by the Jedi.

When the dust settled, the Republic command saw that the electro-proton bomb had successfully disabled the droid armies while leaving the Republic's organic soldiers unharmed. Moments after Skywalker congratulated Boll, however, a sinkhole appeared where the bomb detonated. The sinkhole rapidly grew, taking Republic forces, Dug soldiers, numerous tanks, and part of a fuel pipe system down into a massive crater. Though post-battle cleanup operations went smoothly at first, Doge Urus was unwilling to sign a treaty without the entire Dug Council present, and later, General Windu lost contact with the rescue party in the sinkhole. When investigating the matter, Windu and Skywalker discovered that the explosion had an unintended side effect: the detonation had awoken a dormant Zillo Beast from its underground lair. The ancient creature's sudden appearance made negotiations with the Dug Council even shakier, with Doge Urus insisting on killing it.[4]

When the Jedi presented a hologram of the creature to Doctor Boll and Chancellor Palpatine, Windu recommended transporting it from Malastare to a sanctuary world in the Outer Rim. When Palpatine learned that the Dugs wanted to kill it in return for signing the treaty, he advised that the Jedi do so, but Boll disagreed. Boll pointed out to Palpatine that, as Skywalker had reported, the Zillo Beast had virtually impenetrable scales, which she believed could open new avenues for technological advancements for the Republic, such as synthesizing its scales to create impenetrable armor. Skywalker proposed that a stun weapon could penetrate the gaps in the Zillo Beast's scales, leaving it unconscious but visibly dead, satisfying the Dugs while allowing the creature to be removed from Malastare. Boll backed Skywalker's hypothesis, which convinced the Chancellor to agree. Using several RX-200 Falchion-class tanks, the Republic stunned the Zillo Beast with ion lasers, bringing it into heavy sedation.[4]

The folly of Boll[]

Boll minus one[]

"I'm just not sure where to begin. The fact remains that the beast is indestructible."
"Nothing is truly indestructible, Doctor. Wasn't there something in Malastare fuel that affected the beast?"
"It weakened the Zillo, yes, but—"
"Excellent. I suggest you start there. Doctor, you need to find a way to kill that beast. Or we shall replace you with someone who can."
―Doctor Sionver Boll and Chancellor Palpatine[5]

Doctor Boll escorts the Zillo Beast to the research center on Coruscant.

With the Zillo Beast no longer a threat, Doge Urus relented his crusade to have it killed and agreed to sign Chancellor Palpatine's treaty. Doctor Boll was present during the signing and, afterward, joined the Jedi and the Chancellor to discuss the future of the Zillo Beast. To General Windu's dismay, Palpatine said that the Republic's scientific community wanted the creature studied in a controlled environment on Coruscant, the Republic's capital planet, and instructed Boll and the Jedi to organize the transportation of the sedated Zillo Beast to the capital from Malastare.[4] Heeding the Chancellor's orders, Boll accompanied the Zillo Beast during the voyage to Coruscant, where she oversaw its transit to the Republic Science and Technical Center in Coruscant's naval base. During the process, Boll walked alongside the CLL-M2 binary loadlifter droids as they offloaded the beast from an Acclamator-class assault ship. On the ground outside the massive research center, Boll met with Palpatine, Senate Vice Chair Mas Amedda, and Generals Windu and Skywalker.[5]

General Windu informed Boll that the Zillo Beast had been officially ceded to her control, further adding that he trusted she would handle it carefully. Boll assured him that the creature was a priceless resource and would be well-treated accordingly. With the transit from Malastare complete, the two Jedi departed, leaving Boll with the Chancellor and Vice Chair. Inside the research center, the Zillo Beast was restrained using containment fields and secured to a large observation structure. For Boll to conduct her study safely, a detachment of clone troopers was stationed inside and outside the center. In her experiments, she was aided by several droid personnel under her command, including several binary loadlifters. In one procedure, she ordered a loadlifter to life one of the beast's outer scales so she could draw a blood sample from the flesh underneath. Seeing that the extraction caused the beast pain and discomfort, Boll ordered her droids to stop once they collected the sample.[5]

Dr Boll confers with Palpatine

Doctor Boll and Chancellor Palpatine observe the Zillo Beast on Coruscant.

Shortly after the blood sample was taken, Boll was joined by Palpatine and Amedda, who had come to check on her progress. From her repulsorlift, Boll reported that the Zillo Beast's scales were as strong as initially believed but also light. Boll reiterated her belief that if she could examine the composition of the scales, she could find a way to synthesize them and develop reinforced armor. When the Chancellor rhetorically asked what was stopping her, Boll replied that she would have to remove the scales to fully examine them, a process that would not only be difficult but would also cause the Zillo Beast immense pain. At this, Palpatine questioned whether or not it would be more efficient to euthanize the creature, a suggestion that shocked Doctor Boll. Also taken aback, Amedda asked Palpatine if he was sure about such a decision, and Boll immediately protested. Boll stated that, besides possibly being the last of its kind, the Zillo Beast displayed what she believed could be intelligence, but Palpatine dismissed the notion.[5]

When Palpatine referred to the creature as "just an animal," the beast turned its head slightly and growled, which Boll remarked meant it did not like the Chancellor's comment. The Chancellor looked to Boll and complimented her moral standings but argued that, with increasing casualties, it was morally imperative to hasten the study of the Zillo Beast to prevent further deaths. Although displeased, Boll told Palpatine that she served at his pleasure but voiced her concerns on how to remove the beast's scales, given their strength. Palpatine calmly responded that nothing was indestructible and asked if something in the Malastare fuel affected the creature. Boll confirmed that the fuel had weakened the beast, but as she began to object, Palpatine cut her off and suggested she start there. Before leaving, Palpatine coldly told Boll that she had to find a way to kill the Zillo Beast, or he would replace her with someone who could. Boll silently nodded before returning to the creature, which roared at the Chancellor as he left.[5]

The Zillo Beast raids again[]

"Doctor, were you successful?"
"We have a problem, sir. […] I need time to convert Malastare fuel into more toxin, Chancellor."
"I suggest you hurry, Doctor."
―Doctor Boll warns Chancellor Palpatine that the Zillo Beast broke from its containment[5]

Despite her trepidation, Boll quickly began converting available Malastarian fuel into enough toxic gas she believed could kill the Zillo Beast. While preparing to administer the toxin, Boll was contacted by Chancellor Palpatine for a progress report, as he was under pressure from members of the Senate and the Jedi Order to release the creature. Boll informed Palpatine that she had successfully converted the Malastarian fuel into poison gas, then asked if the Chancellor still wished for her to proceed and kill the Zillo Beast. Palpatine replied that he wished there was an alternative but instructed Doctor Boll to continue the procedure as planned. Boll nodded as the transmission ended, then despondently loaded a gas canister onto a medical droid and watched as it floated to the Zillo Beast's head. Before ordering the droid to commence the euthanization process, Boll quietly spoke to the Zillo Beast, apologizing for what she was about to do and reassuring it that everything would be over soon.[5]


Boll informs Chancellor Palpatine that she is prepared to kill the Zillo Beast.

Boll ordered the medical droid to begin, and it started spraying the poison gas across the beast's head and into its nostrils. Boll looked at her datapad and noted that the Zillo Beast's vital signs were dropping, but as the droid finished spraying it with gas, the beast became aggravated and began moving. The beast lifted its arms, destroying one of the observation tower's walkways and sending a clone trooper over the side. To Boll's horror, the beast pulled its arms free from the containment fields, after which it destroyed the observation tower and headed toward the research center's entrance bay. Boll attempted to fly her repulsorlift out of the creature's path, but its tail slammed into her pod, causing it to crash into the ground. While Boll recovered, the beast broke through the reinforced entrance, destroying several AT-TE walkers stationed outside. The injured Boll, meanwhile, joined the clones as they evacuated the center. Once outside, she heard the Zillo Beast's roar in the distance and saw it had already fled the military base.[5]

Seeing the Zillo Beast rampaging through the streets of Galactic City, Boll immediately contacted the unaware Chancellor Palpatine, who asked if the procedure had been successful. Boll informed Palpatine that there was a problem, and the Chancellor looked outside his office in the Senate Office Building to see the beast's path of destruction on the horizon. With Coruscant endangered, Boll decided that she needed to create enough toxin to kill the Zillo Beast. She informed Palpatine that she would need time to convert higher quantities of Malastarian fuel, and he ordered her to hurry. In the meantime, Republic forces engaged the beast in a bid to slow its path, but to no avail. While the creature directed its path toward the Senate complex, which underwent lockdown protocols,[5] Boll worked tirelessly to make more gas,[10] and the Republic Military began to roll out R2-200 tanks to combat the Zillo Beast. Once she believed she had created enough gas, Doctor Boll notified Palpatine.[5]


Gas bombs developed by Boll are deployed against the rampaging Zillo Beast, killing it.

The Chancellor told Boll that his guards would be with her shortly and that she was to hand the gas over to them immediately. As their transmission ended, Palpatine's escape craft was caught midair by the Zillo Beast, which had reached and scaled the Senate Office Building. At the research facility, a military escort arrived to take Boll to an improvised staging area in the Senate District. Her toxin, now in the form of projectile bombs, was loaded into the cannons of several LAAT/i gunships, but Jedi Grand Master Yoda ordered them to hold their fire until the Chancellor was rescued. Once the Jedi secured Palpatine and brought him out of the monster's vicinity, the order was handed down to deploy Boll's gas bombs. Using flares to distract the Zillo Beast, the Republic gunships fired the bombs into its mouth. Rapidly losing its mobility as it died, the beast fell from the Senate building onto the ground below.[5] Disappointed that her research led to this outcome, Boll approached the creature and comforted it as it died.[10]

The following day, the Zillo Beast's body was loaded onto a platform and led away from the Senate complex before being loaded onto a Republic cruiser. Boll, still at the staging area outside the office building, met with Chancellor Palpatine as he thanked the Jedi for their efforts to rescue him. Boll walked with Papatine and his security detail to a nearby gunship, and the Chancellor congratulated her on her success. As they walked, the Chancellor handed her a datapad, which he stated contained her new orders. To Boll's horror, her new assignment was to clone the Zillo Beast, but Palpatine ignored her questioning and boarded the gunship, after which Boll watched him leave.[5] For the following years, Boll complied with her task and spent part of her research trying to clone the Zillo Beast, but by[10] 19 BBY,[8] her efforts had been unsuccessful. When the Clone Wars came to an end, Palpatine transformed the Republic into the authoritarian Galactic Empire, under which he was no longer in need of Boll's talents.[10]


"These are two halves of the same chip! The Republic used the EPB during the Clone Wars to devastate electronics within a blast radius while leaving organic troopers unharmed. The Separatist defoliator did the opposite, shredding organic molecular bonds to leave lifeless metal behind. Combining them? It's child's play."
―Major Capin Harinar, on the Electro-Proton Bomb/Defoliator[11]

With Boll no longer attached to the project,[10] the research on the Zillo Beast fell into the hands of the newly-created Advanced Science Division, headed by Doctor Royce Hemlock. With the ruthless Hemlock at the helm, as well as the acquisition of Kaminoan technology taken from the planet Kamino's cloning facilities before the Empire destroyed them, the cloning program was able to clone several Zillo Beasts from the original specimen's DNA, which were later held at the secret Tantiss Base on Wayland. Like her Zillo Beast research,[12] Sionver Boll's[4] electro-proton bomb would have a potentially dangerous lineage under the Empire. According to rumors, the Empire created a new superweapon called the Electro-Proton Bomb/Defoliator, which combined Boll's electro-proton bomb and the defoliator,[11] a weapon created by Confederate General Lok Durd during the early Clone Wars[13] that shredded organic matter. The bomb was allegedly developed by Director Orson Krennic of the Imperial Military Department of Advanced Weapons Research, whose lab employed former Separatists.[11]

Zillo Beast Clone

After the rise of the Galactic Empire, Doctor Boll's research on the Zillo Beast went to the Advanced Science Devision, which successfully cloned the creature.

Rumors of the Electro-Proton Bomb/Defoliator reached the highest levels of the Alliance to Restore the Republic, a resistance movement opposed to Emperor Palpatine's reign. Though some dismissed the rumors as "spacer's tales, General Airen Cracken believed that the possibility of the superweapon's existence merited concern. In his report on the subject, Major Capin Harinar stated that combining the electro-proton bomb and the defoliator was child's play and remarked that<ref name="The Rebel Files" /> Boll's weapon, once hailed for its inability to harm organic beings,<ref name="The Zillo Beast" /> was just another half of the same chip as the defoliator. Decades after the Rebel Alliance defeated the Empire in the Galactic Civil War, the classified reports about the Electro-Proton Bomb/Defoliator were unearthed[11] in 34 ABY[14] and fell into the hands of the Resistance, a militia created to combat the First Order, a neo-Imperial junta. After reading Harinar's report, General Caluan Ematt planned to run the information by Resistance intelligence, believing the First Order may have restarted some Imperial superweapon projects.[11]

Long after the Clone Wars, Sionver Boll was still held by some in high regard for her service to the Republic during the war and the work she conducted in weapons development. At some point, an unknown artist, suspected by researchers at the Graf Archive to be the reclusive Ithorian Gammit Chond, had heard stories about "Bivall scientists" who had dealt with the fearsome Zillo Beast during the Clone Wars and drew a depiction of a Bivall in a journal containing sketches of various species. The journal ended up in the Shadow Stacks of the Graf Archive on Orchis 2, where it was eventually restored and given a public release. For the publication, the Archive paired each artwork with data drawn from its library. In the entry on Bivall, Boll was named among those notable of her species. She was noted specifically for the creation of the electro-proton bomb and her studies into the use of the Zillo Beast's scales in military operations.[7]

Personality and traits[]

"I applaud your high moral stance, Doctor. After all, principle is in such short supply these days."
―Chancellor Palpatine commends Sionver Boll[5]

Doctor Sionver Boll

A female Bivall standing at 1.73 meters, Boll had gold eyes and red-and-white colored skin.[4] Boll had a sharp intellect and was renowned for her brilliance in the scientific field. Though her work with the Republic largely focused on weapons development, Boll was an empathetic and moral person and was lauded for her principled stances. She possessed great empathy for the Zillo Beast, both as a specimen and a possibly-sentient being. However, Boll was willing to disregard her personal moral standing on the ethics of studying the beast,[5] and as a result, she learned that there was a dark side to pursuing such dangerous knowledge.[2] Her experiments were not without fault either, as she miscalculated the amount of toxic gas required to kill the monster successfully.[5]

Though subservient to Chancellor Palpatine, Boll was unafraid to challenge him or speak to him with dry sarcasm. She protested the Chancellor's proposal to have the Zillo Beast killed, but when her career future was called into question by his threats to remove her from her position, Boll quickly fell into line and planned to kill the beast as he had ordered. Although she proceeded with her orders to terminate it, she tried to comfort the beast and ease it before attempting to do so. Despite her mistakes,[5] the doctor realized the dangers of her practice[2] following the Zillo Beast's raid on Coruscant and was shocked when given new orders to clone the creature.[5]

Skills and abilities[]

"It's scales are remarkably strong and light. If we could examine their composition, we may be able to synthesize them to reinforce our clone armor."
―Doctor Boll had extensive knowledge in several scientific fields[5]

As a Bivall, Sionver Boll had a naturally sharp intellect and a predisposition to scientific study.[7] In her line of work, Dr. Boll utilized her expertise in various fields with her lab. As a weapons developer for the Galactic Republic, she had a history in military research and engineering, talents which she lent to the creation of the electro-proton bomb and other inventions for use in the Clone Wars.[3] In addition to these abilities, Boll had expertise in biology and chemistry, skills she displayed when studying the Zillo Beast and its scales and when converting Malastarian fuel into a potent toxin strong enough to kill the creature, respectively. She also had some knowledge of cloning and cloning technology.[5]


As the head of her own laboratory,[3] Doctor Boll had access to several droid personnel under her command. She had a number of[5] modified CLL-M2 binary loadlifters, labor droids manufactured by Cybot Galactica,[15] which provided heavy work while she studied the Zillo Beast. For lighter work, Boll was aided by a much smaller model of science droid, which had four limbs and various attachments useful for the examination of the beast. While studying the Zillo Beast, Boll was granted access to the vast Republic Science and Technical Center, where she used repulsorcraft to closely survey the massive creature.[5]

Behind the scenes[]

Sionver Boll first appeared in "The Zillo Beast," the eighteenth episode of the second season of the animated television series Star Wars: The Clone Wars.[16] Directed by Giancarlo Volpe and written by Craig Titley,[4] the episode first aired on April 9, 2010, in the US.[16] Boll was again featured in the following episode, "The Zillo Beast Strikes Back." In both appearances, she was voiced by actress Cara Pifko.[4][5]



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