Call of Duty is a first-person shooter video game franchise published by Activision. Starting out in 2003, it first focused on games set in World War II. Over time, the series has seen games set in the midst of the Cold War, futuristic worlds, and the modern day. The games were first developed by Infinity Ward, then also by Treyarch and Sledgehammer Games. Several spin-off and handheld games were made by other developers. The most recent title, Call of Duty: Modern Warfare II, was released on October 28, 2022.

The series originally focused on the World War II setting, with Infinity Ward developing the first (2003) and second (2005) titles in the series and Treyarch developing the third (2006). Call of Duty 4: Modern Warfare (2007) introduced a new, modern setting, and proved to be the breakthrough title for the series, creating the Modern Warfare sub-series. The game's legacy also influenced the creation of a remastered version, released in 2016. Two other entries, Modern Warfare 2 (2009) and Modern Warfare 3 (2011), were made. The sub-series received a reboot with Modern Warfare in 2019, with a sequel released in 2022. Infinity Ward have also developed two games outside of the Modern Warfare sub-series, Ghosts (2013) and Infinite Warfare (2016). Treyarch made one last World War II-based game, World at War (2008), before releasing Black Ops (2010) and subsequently creating the Black Ops sub-series. Four other entries, Black Ops II (2012), III (2015), 4 (2018), and Cold War (2020) were made, the latter in conjunction with Raven Software. Sledgehammer Games, who were co-developers for Modern Warfare 3, have also developed three titles, Advanced Warfare (2014), WWII (2017), and Vanguard (2021).

As of April 2021, the series has sold over 400 million copies. Meanwhile, the games in the series have consistently released annually to blockbuster-level sales, the series is verified by the Guinness World Records as the best-selling first-person shooter game series. It is also the most successful video game franchise created in the United States and the fourth best-selling video game franchise of all time. Other products in the franchise include a line of action figures designed by Plan B Toys, a card game created by Upper Deck Company, Mega Bloks sets by Mega Brands, and a comic book miniseries published by WildStorm Productions.