Assassin's Creed IV: Black Flag is an 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, Xbox One, and It was later re-released on the Nintendo Switch as part of The Rebel Collection alongside Assassin's Creed Rogue in December 2019.

The plot is set in a fictional history of real-world events and follows the millennia-old struggle between the Assassins, who fight to preserve peace and free will, and the Templars, who desire peace through control. The framing story is set in the 21st century and depicts the player as an employee of Abstergo Industries (a company used as a front by the modern-day Templars), who becomes caught in their conflict with the Assassins.