Monkey D. Luffy's straw hat is the main symbol of the entire series and is the origin of his nickname "Straw Hat Luffy." His straw hat was given to him by his idol, "Red-Haired" Shanks when Luffy was a child, and he promised to give the hat back to Shanks once he becomes a great pirate (or in other words, the Pirate King).

Much later, during the Straw Hat Pirates' departure for Fish-Man Island, it was revealed by Silvers Rayleigh that this straw hat originally belonged to Gol D. Roger.