Darker than Black (Japanese: Darker Than Black ー黒の契約者ー, Hepburn: Dākā Zan Burakku ーKuro no Keiyakushaー, "Darker than Black: The Black Contractor") is a Japanese anime television series created and directed by Tensai Okamura and animated by studio Bones. 25 episodes were broadcast on MBS, TBS and their affiliated stations from April to September 2007. The series is set in a world where a spatial anomaly identified as "Heaven's Gate" appeared in South America and was followed by "Hell's Gate" in Tokyo, altering the sky and wreaking havoc on the landscapes. People with special abilities labeled as Contractors emerged shortly afterwards. The series follows agent Hei and his comrades in the Syndicate organization, operating in a vastly altered version of contemporary Tokyo to uncover the mysteries of Hell's Gate.

The series was adapted into two manga series, which were serialized in Kadokawa Shoten's Monthly Asuka and Square Enix's Young Gangan, respectively. A sequel to the anime series, Darker than Black: Gemini of the Meteor, was broadcast for twelve episodes from October to December 2009. In the sequel, Hei trains new Contractor Suo Pavlichenko and searches for his former ally Yin. DVDs of the series included original video animations titled Darker than Black: Gaiden exploring Hei and Yin's relationship between the first and second seasons. In North America, Darker than Black was licensed by Funimation.

The series was created by Okamura, who was inspired by ninja and spy stories based on ideas he had after creating Wolf's Rain. In contrast to Wolf's Rain heroic cast, Okamura wanted flawed and violent heroes such as the Contractors. While Okamura penned most of the series' contents, he left freedom to other writers, most notably Shōtarō Suga who takes over the work of main writer in the second half. Critical response to Darker than Black was generally positive for its handling of Hei and the other Contractors who fight each other though there was expressure of confusion in regards to the setting and ending.