- "Thank you, Etain. It was fascinating."
- ―Ko Sai's suicide note
Ko Sai was a female Kaminoan, born on the planet Kamino and genetic engineer. She once met with Hego Damask, a Muun individual. Damask brought a Yinchorri subject to Kamino to inquire about using the Yinchorri as the template for a clone army. Ultimately, she and two other Kaminoan scientists were unable to use their science to take out the Yinchorri's natural aggression, and the species was abandoned in favor of Humans.
By the time of the Clone Wars, Ko Sai became Chief Scientist of the creation of the Grand Army of the Republic. It was her responsibility to ensure that the clones were of the highest quality, overseeing all the biological aspects of the project. She also directed the "processing" of the clones that failed to meet her expectations.
Following the First Battle of Kamino, Ko Sai told Yoda more about the source of funding for the army—a man called Tyranus, who happened to be Count Dooku, a former Jedi. At some point, she met with the Supreme Chancellor Palpatine, who wanted her research to extend his life indefinitely. She noted that he disturbed her.
A year and a half into the war, Ko Sai defected to the Separatists and soon, clone commandos and ARC troopers were deployed to find the scientist before she could reveal any cloning information to the Confederacy. However, she quickly abandoned the Separatists as well and became independent, fleeing both the Separatists and the Republic to continue her work in secrecy.
Kal Skirata, his Null-ARCs, Ordo, Mereel, along with Walon Vau also took up the search for the scientist in the hopes that Ko Sai would be able to engineer a full life span for the clone army. After a prolonged search, they found her on Dorumaa, hiding in an underground laboratory.
Sai was unwilling to help them, believing that Skirata would sell her research for to the highest bidder. Ordo, seemingly in a fit of rage, destroyed her research in front of her, leaving the devastated Sai without a legacy. Unknown to her, Ordo and Mereel had made a backup copy of her research, in case Ko Sai never gave them the information they wanted. Without her, they could bring the research to other cloners, such as Arkanian Microtechnologies or the Khommites. Ko Sai, however, was kept ignorant of this fact, in order to leave her broken and more willing to cooperate, hoping for an opportunity to start over with her beloved work.
In exchange for blood samples and multipotent stem cells from Etain Tur-Mukan and Venku's umbilical cord, Ko Sai surrendered some of the gene sequences that would allow for the age reversal to take place. After studying Venku's genome, Ko Sai committed suicide by hanging herself from a rafter, leaving Etain a note thanking her for the opportunity to study such a fascinating genome. Mereel, along with Jaing and Ordo, prepared her for transport to Kamino, last seen moving her corpse into a barn with vibroblades drawn. Skirata later delivered Ko Sai's head to Delta Squad, who were to offer it as proof of her death to convince the Republic and Palpatine to give up searching for Sai and her research.
In 40 ABY, Goran Beviin told Boba Fett that someone killed Ko Sai, saying that most of her corpse was returned to Kamino in pieces, leading Boba to believe that her death was an act of revenge. Later it was discovered that part of her hide was made into a pair of fine gray gloves worn by Jaing Skirata, one of the Null-class ARCs.
Personality and traits
- "We had a dirtbag geneticist like you once. Yes, a mad Mando scientist. Liked experimenting with kids. He's been dust for millennia, but we still know what the name Demagol means. The irony is that it can mean either 'sculptor of flesh' or 'butcher', so I reckon you two would have had a lot of cozy chats about how to screw up living beings."
- ―Kal Skirata to Ko Sai, noting the latter's similarities with cruel Mandalorian Neo-Crusader Demagol
Ko Sai, like most Kaminoans, was a very cold and calculating sentient due to Kaminoan culture. Kal Skirata told Etain a story about a Kaminoan child who was born with green eyes, whose mother had hidden it in one of the clone training areas. Kaminoan society permitted only gray, blue, or yellow eyes to determine caste, so Ko Sai had the child found and killed only because it possessed an undesirable trait. She referred to all of her clones as "units". After two years of experimentation with the first batch of clones, the six Null ARCS, she ordered them to be terminated because they had a flaw; they stubbornly questioned authority. They were saved by Kal Skirata and Jango Fett, ostensibly for use as special intelligence operatives. Skirata raised and trained them personally, but all six never fully recovered from the horrors of Ko Sai's experiments. Even when held in captivity by Skirata and the Nulls, she was still her old self; in order to spite her clone captors, she committed suicide to deny them information.
- Darth Plagueis
- Darth Plagueis audiobook
- Star Wars: Episode II Attack of the Clones (First appearance)
- Star Wars: Republic Commando
- Republic Commando: Triple Zero (Mentioned only)
- "Odds" – Star Wars Insider 87 (Mentioned only)
- Republic Commando: True Colors
- Order 66: A Republic Commando Novel (Mentioned only)
- Labyrinth of Evil (Mentioned only)
- Imperial Commando: 501st (Mentioned only)
- Legacy of the Force: Bloodlines (Mentioned only)
- Legacy of the Force: Sacrifice (Mentioned only)
- Legacy of the Force: Revelation (Indirect mention only)
- Star Wars: Attack of the Clones: The Visual Dictionary
- The Official Star Wars Fact File 35 (CLO4, Creation of the Clone Army)
- The Official Star Wars Fact File 91 (CLO2, Clone Troopers)
- Geonosis and the Outer Rim Worlds
- The Complete Star Wars Encyclopedia
- Star Wars: The Complete Visual Dictionary
- The Essential Reader's Companion