Assassin's Creed IV: Black Flag is a 2013 action-adventure video game developed by Ubisoft Montreal and published by Ubisoft. It is the sixth major installment in the Assassin's Creed series. Its historical timeframe precedes that of Assassin's Creed III (2012), but its modern-day sequences succeed III's own. Black Flag was originally released for PlayStation 3, Xbox 360, and Wii U in October 2013 and a month later for PlayStation 4, Windows, and Xbox One. It was later ported to the Nintendo Switch as part of The Rebel Collection alongside Assassin's Creed Rogue in December 2019. The game was released for Google Stadia in September 2021.

Assassin's Creed is a historical action-adventure video game series and media franchise published by Ubisoft and developed mainly by its studio Ubisoft Montreal using the game engine Anvil and its more advanced derivatives. Created by Patrice Désilets, Jade Raymond, and Corey May, the Assassin's Creed video game series depicts a fictional millennia-old struggle between the Order of Assassins, who fight for peace and free will, and the Knights Templar, who desire peace through order and control. The series features historical fiction, science fiction, and fictional characters intertwined with real-world historical events and historical figures. In most games, players control a historical Assassin while also playing as an Assassin Initiate or someone caught in the Assassin–Templar conflict in the present-day framing story. Considered a spiritual successor to the Prince of Persia series, Assassin's Creed took inspiration from the novel Alamut by the Slovenian writer Vladimir Bartol, based on the historical Hashashin sect of the medieval Middle East.