Theocritus, a Greek poet of the third century B.C. He is credited with inventing the pastoral, a literary composition concerning country life. The pastorals of Theocritus are in the form of idylls, short lyrical poems, many of them dialogues between shepherds. His idylls treated the lives of shepherds in an idealized manner, but he introduced realistic details. He also wrote a number of idylls on mythological subjects, such as the life of the hero Hercules.

Theocritus had great influence on later poets, including Virgil, Spenser, Milton, Shelley, and Tennyson.

Theocritus was born in Syracuse, Sicily. While at the court of Ptolemy Philadelphus in Alexandria, he was the foremost poet of the Alexandrian School.