Henryk Adam Aleksander Pius Sienkiewicz (US: shen-KYAY-vitch, -⁠KYEV-itch, Polish: [ˈxɛnrɨk ˈadam alɛkˈsandɛr ˈpjus ɕɛnˈkʲɛvit͡ʂ]), also known by the pseudonym Litwos, was an epic Polish writer renowned for his historical novels, such as the Trilogy series and especially for his internationally known best-seller Quo Vadis (1896).

Born into an impoverished Polish noble family in Russian-ruled Congress Poland, Sienkiewicz began publishing journalistic and literary pieces in the late 1860s. In the late 1870s, he traveled to the United States, sending back travel essays that won him popularity with Polish readers. In the 1880s, he began serializing novels that further increased his popularity, soon becoming one of the most popular Polish writers of the turn of the 19th and 20th centuries. His works, translated into numerous languages, gained him international renown, culminating in his receipt of the 1905 Nobel Prize in Literature for his "outstanding merits as an epic writer."

Many of his novels remain in print. In Poland, he is best known for his "Trilogy" of historical novels – With Fire and Sword, The Deluge, and Sir Michael – set in the 17th-century Polish–Lithuanian Commonwealth; internationally, he is known for Quo Vadis, set in Nero's Rome. The Trilogy and Quo Vadis have been filmed multiple times, with Hollywood's 1951 version receiving the most international recognition.