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
Jacob L. Wright, Associate Professor of Hebrew Bible at Emory University, has written that the most popular legends about David, including his killing of Goliath, his affair with Bathsheba, and his ruling of a United Kingdom of Israel rather than just Judah, are the creation of those who lived generations after him, in particular those living in the late Persian or Hellenistic periods.