KL-03, also known as K-L, functioned as both an admin unit and a protocol droid under the ownership of Ty Yorrick, a former Jedi who operated as a lightsaber-for-hire during the High Republic Era. KL-03 expressed a preference for the nickname "Klo." Similar to how Yorrick viewed her other belongings, including her astromech droid R0-VR and her starship, she found no value in assigning a name to the admin unit, perceiving the droid as merely a tool to which she felt no need to develop an emotional connection. Klo possessed a sarcastic demeanor and often rebuked Yorrick, suggesting she was more robotic than Klo herself.
Cavan Scott conceived KL-03 as a component of the Star Wars: The High Republic publishing project. The droid made its initial appearance in Ty Yorrick's Characters of Star Wars: The High Republic video, released on April 15, 2021, and was later identified in the novel The High Republic: The Rising Storm, penned by Scott and released on June 29, 2021. The admin unit's visual design drew inspiration from concept artwork created by Matthew Savage for L3-37 in the film Solo: A Star Wars Story.