Le flibustier is a comédie lyrique (lyric comedy) in three acts, composed by César Cui during 1888-1889. Although the title can translate as The Pirate or The Buccaneer, this is no swashbuckling action-drama, but an idyllic domestic comedy of mistaken identity.

The opera is based on the like-named play by Jean Richepin, who wrote the libretto, and is dedicated to La Comtesse de Mercy-Argenteau. It premiered at the Opéra-Comique in Paris on 22 February 1894, and played for four performances. It was revived in 1908 in a production by students at the Moscow Conservatory under the conductorship of Mikhail Ippolitov-Ivanov, and a Russian edition of the piano-vocal score was printed under the title У моря (U morja = By the Sea). Nevertheless, despite the composer's own special fondness for this work, Le Flibustier seems never to have been performed again and never became part of the standard operatic repertoire.

In the year of its premiere, the composer contributed a rare biographical article entitled "Flibustier in Paris" about his experiences with this opera published in the Russian periodical Knizhki nedeli.

The composer extracted an orchestral suite from this work consisting of the initial Prelude, the Dances that close Act I, and the March in Act III.

The French title of the opera has been transliterated into Cyrillic variously as Флибустьер or Флибюстье. Russian renderings of the French title include Морской разбойник (Morskoj razbojnik) and Пират (Pirat), both meaning "pirate."