Goliath
Goliath is described in the biblical Book of Samuel as a Philistine giant defeated by the young David in single combat. The story signified Saul's unfitness to rule, as Saul himself should have fought for the Kingdom of Israel.
David
The first book of Samuel portrays David as the youngest of the eight sons of Jesse of Bethlehem. His mother is not named in any book of the Bible, but the Talmud identifies her as Nitzevet daughter of Adael. When the story was retold in 1 Chronicles (4th century BCE) he was made the youngest of seven sons and given two sisters, Zeruiah and Abigail. The Book of Ruth (possibly also 4th century BCE) traces his ancestry back to Ruth the Moabite.