A giant soldier in the Philistine army that challenged the Israeli army under King Saul, to send a man against him in single combat to decide which side would claim victory. This went on for 40 days until young David arrived, bringing food for his three older brothers in the ranks.
When David heard Goliath's challenge, he accepted, and armed with only a slingshot and five stones, he met Goliath at the battlefield between the two armies, and killed Goliath with a single stone from the slingshot. The stone imbedded in Goliath's forehead.
The Philistine army was routed by the Israelis after this, and this event began the career of David, who later became Israel's most famous King. Goliath's height was listed at six cubits and a span. If a cubit is about 18 inches as some think, Goliath would have been over nine feet tall.
The story of Goliath is found in 1 Samuel 17:4-51. Note: In 2 Samuel 21:15-22 there are four more giants killed by the Israelis in battle, they were all from the tribe of giants in Gath. Some people believe, the five stones David picked up to kill Goliath, was a forecast of the five giants that were eventually killed by David and his men.