Pelethites

mentioned always along with the Cherethites, and only in the time of David. The word probably means "runners" or "couriers," and may denote that while forming part of David's bodyguard, they were also sometimes employed as couriers (2Sam 8:18; 20:7; 20:23; 1Kings 1:38; 1:44; 1Chr 18:17). Some, however, think that these are the names simply of two Philistine tribes from which David selected his body-guard. They are mentioned along with the Gittites (2Sam 15:18), another body of foreign troops whom David gathered round him.

EBD - Easton's Bible Dictionary