In Assassin's Creed IV: Black Flag, the pirate who becomes an Assassin is named Edward Kenway.
Edward is a Welsh privateer and pirate active during the Golden Age of Piracy in the early eighteenth century. He initially seeks wealth and status rather than the Assassin Brotherhood's cause, but his encounters with Assassins and Templars gradually change his priorities.
Edward is also the grandfather of Haytham Kenway and the ancestor of Ratonhnhaké:ton, the protagonist of Assassin's Creed III. This family connection links Black Flag's Caribbean story with the American Revolution setting of the later game. Edward's surname is sometimes confused with those of other Kenway characters, but his first name is the requested answer.