Charles Ellicott Commentary 1 Samuel 17:23

"And as he talked with them, behold, there came up the champion, the Philistine of Gath, Goliath by name, out of the ranks of the Philistines, and spake according to the same words: and David heard them." — 1 Samuel 17:23 (ASV)

The Philistine of Gath. —There is a difficulty connected with the Philistine giant’s name, for we read in 2 Samuel 21:19 that Goliath of Gath, the giant, the staff of whose spear was like a weaver’s beam, was slain by Elhanan, the son of Jaare-oregim, a Bethlehemite, after David was made king. It is possible that Goliath was a general designation of these monstrous descendants of the ancient Anakim in Gath; but Ewald suggests that the name Goliath really only belongs to the giant slain by Elhanan, some years after the exploit of the youthful son of Jesse, and that it was transferred in error to the “champion” whom David slew (who is, moreover, generally called simply “the Philistine”) when his proper name had been lost.