Issan Len was a cyberneticist in Cloud City on Bespin who created the prototype droid X0-X1, in an experiment to create a droid that could self-reprogram and manage the myriad administrative functions of a space station. X0-X1 took control of Cloud City upon its activation, and forced the protocol droid F-3PO to kill Doctor Len, despite F-3PO's misgivings.