Gad was the seventh son of Jacob and father of the tribe of Gad, one of the twelve tribes of Israel. His mother was Zilpah, Jacob's concubine and Leah's slave. Gad's name comes from the Hebrew word troop. Leah named him Gad, saying "A troop is coming." He was part of the plot to sell Joseph to Egypt and later sent to Egypt to buy corn during the famine in Canaan. Gad later moved to Egypt and lived there with his seven sons. Jacob blessed Gad on his deathbed, saying: "Raiders will raid Gad, but he will raid at their heel" (Genesis 49:19).
Sources: Bridger, David. Ed. The New Jewish Encyclopedia, NY: Behrman House, 1976; Navigating the Bible II