In Cold Blood is a non-fiction novel by American author Truman Capote, first published in 1966. It details the 1959 murders of four members of the Clutter family in the small farming community of Holcomb, Kansas.

Capote learned of the quadruple murder before the killers were captured, and he traveled to Kansas to write about the crime. He was accompanied by his childhood friend and fellow author Harper Lee, and they interviewed residents and investigators assigned to the case and took thousands of pages of notes. Killers Richard Hickock and Perry Smith were arrested six weeks after the murders and later executed by the state of Kansas. Capote ultimately spent six years working on the book.

In Cold Blood was an instant success and is the second-best-selling true crime book in history, behind Vincent Bugliosi's Helter Skelter (1974) about the Charles Manson murders. Some critics consider Capote's work the original non-fiction novel, although other writers had already explored the genre, such as Rodolfo Walsh in Operacin Masacre (1957). In Cold Blood has been lauded for its eloquent prose, extensive detail, and triple narrative which describes the lives of the murderers, the victims, and other members of the rural community in alternating sequences. The psychologies and backgrounds of Hickock and Smith are given special attention, as is the pair's complex relationship during and after the murders. In Cold Blood is regarded by critics as a pioneering work in the true crime genre, although Capote was disappointed that the book failed to win the Pulitzer Prize. Parts of the book differ from the real events, including important details.

Holcomb is a city in Finney County, Kansas, United States. As of the 2020 census, the population of the city was 2,245.