Villanelle, birth name Oxana Vorontsova or Oksana Astankova is a fictional character in Luke Jennings' novel Codename Villanelle (2018), its sequels Killing Eve: No Tomorrow (2019) and Killing Eve: Die For Me (2020), and the BBC America television series adaptation Killing Eve (2018–2022) in which she is portrayed by English actress Jodie Comer. She is a psychopathic assassin who works for a crime syndicate called The Twelve, and the archenemy of British intelligence agent Eve Polastri. Their mutually obsessive relationship is the main focus of both the novels and the TV series. The character and Comer's performance have received universal critical acclaim, with Villanelle widely being considered the show's breakout character and one of the most popular and acclaimed characters on television.

Codename Villanelle is a 2017 thriller novel by British author Luke Jennings. A compilation of four serial e-book novellas published from 2014 to 2016, the novel was published in the United Kingdom by John Murray as an e-book on 29 June 2017, followed by hardcover and paperback versions on 24 August 2017. Codename Villanelle is the basis of the BBC America/BBC Three television series Killing Eve (2018–2022).