HK-58 Besh, an assassin droid of the HK-series, served HK-47 as he tried to seize control of the world of Mustafar. A band of spacefarers ultimately destroyed it before proceeding to vanquish HK-47.
HK-58 Besh shared a connection with its counterpart, Aurek; should either Aurek or Besh be defeated, the surviving unit would reactivate and resume combat unless destroyed within a five-second window. Similar to the smaller HK-77, both HK-58 Besh and Aurek employed disruptor weaponry integrated into their arms.