Yizhar Smilansky (Hebrew: יזהר סמילנסקי‎, 27 September 1916 – 21 August 2006), known by his pen name S. Yizhar (Hebrew: ס. יזהר‎), was an Israeli writer and politician.

Yizhar Smilansky was born in Rehovot to a family of writers. His great uncle was Israeli writer Moshe Smilansky. His father, Zev Zass Smilensky, was also a writer. After earning a degree in education, Yizhar taught in Yavniel, Ben Shemen, Hulda, and Rehovot.

From the end of the 1930s to the 1950s, Yizhar published short novellas, among them Ephraim Goes Back to Alfalfa, On the Edge of the Negev, The Wood on the Hill, A Night Without Shootings, Journey to the Evening's Shores, Midnight Convoy, as well as several collections of short stories. His pen name was given to him by the poet and editor Yitzhak Lamdan, when in 1938 he published Yizhar's first story Ephraim Goes Back to Alfalfa in his literary journal Galleons. From then on, Yizhar signed his works with his pen name.

In 1949, he published the novella Khirbet Khizeh, in which he described the expulsion of Palestinian Arabs from their village by the IDF during the 1948 Arab-Israeli War. It became a best-seller and in 1964 was included in the Israeli high school curriculum. In 1978, a controversy arose after a dramatization of Khirbet Khizeh by director Ram Loevy was aired on Israeli television. In 1988, when Benny Morris published The Birth of the Palestinian Refugee Problem, 1947–1949, S. Yizhar "announced himself as the man who had laid bare the original sin of the State of Israel".