The Lancet is a weekly peer-reviewed general medical journal. It is one of the world's oldest and best known general medical journals. It was founded in 1823 by Thomas Wakley, an English surgeon who named it after the surgical instrument called a lancet, as well as after the architectural term "lancet arch", a window with a sharp pointed arch, to indicate the "light of wisdom" or "to let in light".

The Lancet publishes original research articles, review articles ("seminars" and "reviews"), editorials, book reviews, correspondence, as well as news features and case reports. The Lancet has been owned by Elsevier since 1991. As of 2015, the editor-in-chief is Richard Horton. The journal has editorial offices in London, New York, and Beijing.