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.
Book of Gad the Seer
The Book of Gad the Seer is a presumed lost text, supposed to have been written by the Biblical prophet Gad, which is mentioned at . The passage reads: "Now the acts of David the king, first and last, behold, they are written in the book of Samuel the seer, and in the book of Nathan the prophet, and in the book of Gad the seer." These writings of Nathan and Gad may have been incorporated into 1 and 2 Samuel.