Shammah the Harodite - There are several varieties in the names of the following shalishim; which may be seen by comparing these verses with Ch1 11:27.

Zelek the Ammonite,.... Who was so either by birth, and became a proselyte; so the Targum says, he was of the children of Ammon; or is so called, because he had sojourned some time in their land, or had done some exploits against them; unless he was of Chepharhaammonai, a city of the tribe of Benjamin, Jos 18:24,

Naharai the Beerothite; native of Beeroth, a city in the same tribe, Jos 18:25,

armourbearer to Joab the son of Zeruiah; Joab had ten of them, this perhaps was the chief of them, Sa2 18:15; who was advanced to be a captain, and therefore has a name and place among the thirty, very likely for some military, exploits performed by him; he is in the list of David's worthies, though not Joab his master, as before observed; the reason of Joab being left out is either because he was over them all, as before noted; according to Josephus (t), Uriah the Hittite, after mentioned, was an armourbearer to Joab.

(t) Antiqu. l. 7. c. 7. sect. 1.