Elhanan, son of Jair
Elhanan son of Jair-Oregim the Bethlehemite ( "’Elḥānān ben-Ya‘rê ’Ōrəḡîm Bêṯhallaḥmî") appears in 2 Samuel 21:19, where he is credited with killing Goliath. As this contradicts the better-known story in 1 Samuel 17 in which it is the famous David who kills Goliath, the 4th century BC Book of Chronicles explains the second Goliath by saying (20:5) that Elhanan "slew Lahmi the brother of Goliath", possibly constructing the name Lahmi from the last portion of the word "Bethlehemite" (""beit-ha’lahmi"). The King James Bible translators modified 2 Samuel 21:18–19 to make it read as if Elhanan had slain Goliath's brother: "And there was again a battle in Gob with the Philistines, where Elhanan the son of Jaare–oregim, a Beth–lehemite, slew "the brother of" Goliath the Gittite, the staff of whose spear was like a weaver's beam", although the Hebrew text at this point makes no mention of the word "brother"; the medieval Jewish authors of the Targum Jonathan solved the problem by explaining Elhanan as an alternative name for David. However, this makes it difficult to explain why David is called "Elhanan" in verse 19 but consistently "David" in the verses that surround it (15, 16, 17, 21, 22). The most widely accepted explanation is that the storytellers have displaced the deed from the obscure Elhanan to the more famous character, David.
Goliath
In Pseudo-Philo, believed to have been composed between 135 BC and 70 AD, David picks up seven stones and writes on them his father's name, his own name, and the name of God, one name per stone; then, speaking to Goliath, he says "Hear this word before you die: were not the two woman from whom you and I were born, sisters? And your mother was Orpah and my mother Ruth ..." After David strikes Goliath with the stone he runs to Goliath before he dies and Goliath says "Hurry and kill me and rejoice." and David replies "Before you die, open your eyes and see your slayer." Goliath sees an angel and tells David that it is not he who has killed him but the angel. Pseudo-Philo then goes on to say that the angel of the Lord changes David's appearance so that no one recognizes him, and thus Saul asks who he is.