The Clone Wars, also known as the Separatist Crisis, is a fictional three-year conflict in the Star Wars franchise by George Lucas. Though mentioned briefly in the first Star Wars film (A New Hope, 1977), the war itself was not depicted until Attack of the Clones (2002) and Revenge of the Sith (2005). The Clone Wars are also the setting for three eponymous projects: a 2D animated series (2003–2005), a 3D film (2008), and a 3D animated series (2008–2014, 2020). They have featured in numerous Star Wars books, comics and games.

Within the Star Wars narrative, the Clone Wars involve a three-year war fought to prevent thousands of planetary systems from seceding from the Galactic Republic and joining the Confederacy of Independent Systems (CIS), colloquially referred to as the Separatists or Separatist Alliance. The Republic uses an army of clone troopers led by the Jedi Order against the Separatist battle droid army. The conflict was a scheme by the Republic's Supreme Chancellor Palpatine, secretly the evil Sith Lord Darth Sidious, seeking to implement the Sith's long-term plans to wipe out all Jedi and take over the galaxy. Palpatine intended this by giving the clone troopers a secret executive command, "Order 66" (in the form of a control chip) embedded in their brains, instantly making clones perceive their Jedi officers as traitors and kill them. He succeeded in issuing the command in Revenge of the Sith promptly leading to the deaths of numerous Jedi around the galaxy, allowing Palpatine to gain total power and ultimately convert the democratic Galactic Republic into the fascist autocratic Galactic Empire, a reign controlled through a military–industrial complex and featured in the original trilogy.

Lucas used the Clone Wars narrative to answer questions about the original trilogy, such as how the Empire originated and how Anakin Skywalker became Darth Vader. The political and military events of the Clone Wars draw inspiration from such real-world conflicts and historical events, as transition of the Roman Republic to the Roman Empire, the American Civil War, the First and Second World Wars, as well as contemporary events such as the war on terror and the Bush administration during the early 21st century.

The first reference to the Clone Wars is in Star Wars creator George Lucas' third draft of the first film, which mentions the grizzled cyborg General Kenobi's "diary of the Clone Wars". The wars were mentioned twice briefly in the final version of the film, referring to Obi-Wan Kenobi as a general who served Leia Organa's (then-unnamed) father Bail Organa during the conflict. In drafting The Empire Strikes Back (1980), Lucas considered introducing a clone character who had been involved with the Clone Wars. Leigh Brackett's first draft of the film initially developed Lando Calrissian as a clone from a planet of clones involved in the Clone Wars mentioned in A New Hope and were nearly made extinct by the war. Boba Fett was also initially considered as being from a group of shocktroopers nearly wiped out by Jedi during the Clone Wars. However, these concepts were not included in the final version of the film. Lucas was more guarded about the details of the Clone Wars than any other element of Star Wars, even making them off-limits to licensed products and books.

Lucas has noted that Palpatine's rise to power is similar to that of Adolf Hitler in Nazi Germany; as Chancellor of Germany, the latter was granted "emergency powers", as is Palpatine. Lucas has also said that one of the primary influences for the political backdrop behind the Clone Wars, and all of Star Wars, was the Vietnam War and Watergate scandal era, when leaders embraced corruption for what they thought was the best course of action. In 2002, Lucas said:

All democracies turn into dictatorships—but not by coup. The people give their democracy to a dictator, whether it's Julius Caesar or Napoleon or Adolf Hitler. Ultimately, the general population goes along with the idea. What kinds of things push people and institutions in this direction? That's the issue I've been exploring: how did the Republic turn into the Empire? ... How does a good person go bad, and how does a democracy become a dictatorship?

The clone forces shown at the conclusion of Attack of the Clones comprised the largest digital army created for a film at that point. Lucas proposed to concept artists that Revenge of the Sith would open with a montage of seven battles on seven planets. Lucas then radically re-organized the plot; instead of opening the film with various Clone Wars battles, Lucas decided instead to focus on Anakin Skywalker. The absence of the "seven battles on seven planets" in part led to Lucas's decision to launch the CGI-animated Clone Wars television series; Lucas said the cartoon could "do better" at depicting the conflict.

The Clone Wars was first depicted in Attack of the Clones, the release of which brought an end to Lucas's embargo on licensed material set during the era. Numerous novels, comic books, and video games exploring the conflict have been sanctioned by Lucas Licensing.