Wars at Gezer, Philistine territory; giants (Rephaim descendants) defeated by David's mighty men, not David.
Giants and killers:
Sippai (Sipai): Killed by Sibbechai (Sibekai) the Hushathite, commander of 24,000.
Lahmi: Brother of Goliath (Gittite); spear shaft like weaver's beam (~2.5" thick, 12+ ft long, 15 lb head); killed by Elhanan son of Jair (one of the 30 mighty men).
Unnamed giant at Gath: Great stature, 24 fingers/toes (6 per hand/foot); defied Israel; killed by Jonathan, son of Shimeah (David's brother).
Parallels 2 Samuel 21:15-22 (includes Ishbi-benob, killed by Abishai saving David).
Giants (Rephaim/Nephilim lineage): Post-flood race from angels mingling with humans (Genesis 6); fought by Abraham (Genesis 14), Moses (Og, Deuteronomy 3:11); anti-God, linked to occult/chaos.