24 is an American action-drama television series created by Joel Surnow and Robert Cochran for Fox. The series features an ensemble cast, with Kiefer Sutherland starring as American counter-terrorist federal agent Jack Bauer. Each season covers 24 consecutive hours using the real time method of narration, which is emphasized by the display of split screens and a digital clock. Multiple ongoing plot lines of intersecting relevance are covered, with Bauer's plot line serving as the link throughout. The show premiered on November 6, 2001, and spanned 204 episodes over nine seasons, with the series finale broadcast on July 14, 2014. In addition, the television film 24: Redemption aired between seasons six and seven, on November 23, 2008. 24 is a joint production by Imagine Television and 20th Century Fox Television.

At the start of the series, Bauer is already a highly proficient agent with an "ends justify the means" approach. This means that he will usually threaten, disregard and lie to anyone who refuses to cooperate with him. Throughout the series, the plot elements contain both a political thriller and serial drama, with each episode typically ending on a cliffhanger. Bauer uses people on both sides of the law in his attempts to prevent terrorist attacks and bring down those responsible, sometimes at great personal expense. These attacks include presidential assassination attempts, bomb detonations, bioterrorism, cyberwarfare, as well as conspiracies that involve government and corporate corruption.

24 received generally positive reviews, with the fifth season being universally praised by critics. However, the series was criticized for perceived Islamophobia and glorification of torture. The show won numerous awards throughout its run, including Best Drama Series at the 2004 Golden Globe Awards and Outstanding Drama Series at the 2006 Primetime Emmy Awards. In May 2013, it was announced that 24 would return with a 12-episode limited series titled 24: Live Another Day, which aired from May 5 to July 14, 2014, bringing the episode count to 204. A spin-off series, 24: Legacy, premiered on February 5, 2017, lasting a single 12-episode season. 24 is the longest-running American espionage- or counterterrorism-themed television drama, surpassing both Mission: Impossible and Britain's The Avengers.