In the year 21 BBY, within the Petranaki arena of Geonosis, Count Dooku brought to life Jek 15, a Force-sensitive clone of Jek-14 who was Human. He was intended to spearhead a Sith clone troopers army, but the Clone-amatic 11-38 cloning device produced a defective result. Jek 15 emerged significantly smaller and weaker than Jek-14. Despite these flaws, Jek 15 remained loyal to the Sith, but was ultimately defeated by Yoda and Obi-Wan Kenobi. The failure of Jek 15 and the Clone-amatic 11-38 led to the device's replacement with a new and improved Clone-amatic.
From the genetic template of Jek-14, a Force-sensitive Human male clone, came Jek 15, a clone created by Count Dooku. This occurred around 21 BBY inside the Petranaki arena on the planet of Geonosis using the cloning device known as the Clone-amatic 11-38. He was introduced to the Sith's allies as the intended second member of a Sith clone troopers army, following Jek-14. Upon his emergence, he declared his allegiance to the Sith and promptly attacked Viceroy Nute Gunray with Force lightning. However, Jek 15 was defective and lacked the power of his predecessor, his Force lightning merely tickling Gunray. Darth Sidious expressed his anger to Dooku, who explained that he was still working on fixing some imperfections.
After the cloning attempt failed, Obi-Wan Kenobi, a Jedi Master who was disguised, and Yoda, a Jedi Grand Master, revealed themselves. Jek 15 engaged the two Jedi, first attacking Yoda with Force lightning. Yoda simply picked up the tiny clone and tossed him aside. Later, Jek 15 shifted his focus to Kenobi, clinging to his legs and forcing the Jedi to hop around while fighting Dooku and General Grievous. Following Jek-14's capture of Yoda, pressure from the old Jedi Master and Dooku to choose a side led Jek-14 to flee in search of solitude. In doing so, he detonated the sand cell in which he had trapped Yoda, and Jek 15 was caught in the blast's shockwave.
The Clone-amatic 11-38, responsible for Jek 15's creation, was subsequently replaced by a new and improved Clone-amatic that was more efficient and produced non-defective clones. However, Jek-14 used his Force abilities to transform all clones created by the new device into miniature versions of himself, identical to Jek 15. Jek-14 then destroyed each of these tiny clones with Force lightning.
Jek 15 was nearly identical to Jek-14, sharing a similar appearance, Force-sensitivity, and abilities. He had black hair, tan skin, and glowing blue eyes, along with a glowing blue left arm. The primary difference was Jek 15's size, being shorter than Yoda's waist. Despite his small stature, Jek 15 was fierce and aggressive towards his enemies, particularly the Jedi Obi-Wan Kenobi and Yoda, due to his loyalty to the Sith. He seemed unaware of his size and was confused by others' reactions to it.
Jek 15 was supposed to possess the same powers and strength as Jek-14, but he was significantly weaker. He could generate Force lightning from his left arm, but it was far less effective, producing a laser-like beam that tickled rather than harmed. This beam also emitted a distinct beeping sound. However, Jek 15's small size allowed him to cling to larger individuals like Kenobi.
Jek 15 wore a precursor to Phase II clone trooper armor, nearly identical to Jek-14's but white with red markings. Like Jek 15 himself, the armor was much smaller than Jek-14's, fitting his size. Jek 15 emerged from the Clone-amatic 11-38 already wearing his armor.
Jek 15 appeared in "Menace of the Sith," the second episode of LEGO Star Wars: The Yoda Chronicles, which was broadcast on Cartoon Network on September 4, 2013. Brian Dobson provided his voice, as he did for Jek-14, but it was altered to a higher pitch. The credits list Jek 15 as "Jek Clone," but his name is visible on a Clone-amatic 11-38 screen, even though it's not explicitly mentioned in the episode.