The Scholia on Theocritus are a body of ancient and medieval scholarly notes, not written by a single person. They are the cumulative work of many generations of grammarians and commentators, beginning with scholars from Alexandria in the 3rd and 2nd centuries BCE and continuing through the Byzantine era. These notes were compiled and preserved in the margins of medieval manuscripts containing the poems of the Hellenistic Greek poet Theocritus.

The scholia serve as a detailed commentary on Theocritus's Idylls. They include explanations of his distinctive Doric dialect, clarify mythological and geographical references, discuss variant readings of the text, and offer literary interpretations. According to modern scholars, this collection is a composite of many sources, some potentially deriving from the work of famous ancient critics whose own writings are now lost.

This compilation is historically vital for several reasons. It provides a crucial window into how ancient scholars edited and analyzed texts, preserving the methods of the influential Alexandrian library tradition. For readers today, the scholia are an indispensable tool for understanding Theocritus's often challenging poetry, illuminating his language, context, and meaning. Furthermore, the transmission of these notes in Byzantine manuscripts was essential for preserving Theocritus's work itself and for passing classical learning on to the Renaissance.