Lieutenant Junior Grade Endel was a male Kelyan Starfleet officer who served as a security officer aboard the Federation starship USS Enterprise in the 2250s, as one of the four assistant security chiefs that reported to Security Chief Orloff.
When the Enterprise journeyed to Areta, Endel was among the personnel Lieutenant Commander Orloff consulted with trying to find options for dissuading Captain Christopher Pike from beaming down alone and unarmed. (TOS novel: Vulcan's Glory)