The hero known for slaying the giant Goliath in mythology is David. In the biblical tale, David, a young shepherd, defeats Goliath, a Philistine warrior, using a simple sling and a stone, symbolizing the triumph of the underdog against overwhelming odds. This story embodies themes of faith, courage, and divine intervention, illustrating that true strength lies not in size but in the heart and spirit. David's victory established him as a legendary figure in history, representing human potential and the importance of resilience in the face of challenges.