Leonid Anatolievich Levin (/ˌleɪ.oʊˈniːd ˈlɛvɪn/ LAY-oh-NEED LEV-in; Russian: Леони́д Анато́льевич Ле́вин [lʲɪɐˈnʲit ɐnɐˈtolʲjɪvʲɪtɕ ˈlʲevʲɪn]; Ukrainian: Леоні́д Анато́лійович Ле́він [leoˈn⁽ʲ⁾id ɐnɐˈtɔl⁽ʲ⁾ijowɪtʃ ˈlɛwin]; born November 2, 1948) is a Soviet-American mathematician and computer scientist.

Levin was awarded the Knuth Prize in 2012[3] for his discovery of NP-completeness and the development of average-case complexity.

His life is described in a chapter of the book Out of Their Minds: The Lives and Discoveries of 15 Great Computer Scientists.

Levin's journal article on this theorem was published in 1973;[6] he had lectured on the ideas in it for some years before that time (see Trakhtenbrot's survey),[7] though complete formal writing of the results took place after Cook's publication.

Levin was awarded the Knuth Prize in 2012[3] for his discovery of NP-completeness and the development of average-case complexity.