Telephus the Grammarian was a Greek scholar who lived and worked during the 2nd century CE, a period of the Roman Empire. His profession was that of a grammarian, meaning he was an expert in the Greek language and its literature, likely working within the educational systems of the eastern Roman world. Almost nothing is known about his personal life. The identification of him with a Telephus from the city of Pergamon is uncertain and not accepted by all scholars.

He is known for a single work, titled On Diction in Homer. This was a specialized treatise analyzing the vocabulary and language used in the epic poems of Homer. The book itself has not survived intact. It exists only in fragments, which were preserved by later scholars who quoted him in their own works. These fragments are found primarily in the marginal notes (scholia) of medieval manuscripts of Homer and in ancient dictionaries.

According to modern scholars, Telephus represents a minor but typical figure in the long tradition of ancient literary scholarship. His significance lies in his contribution to Homeric studies, showing how grammarians meticulously analyzed canonical texts. The survival of his work only through quotations demonstrates a common pattern: the notes of individual experts were often absorbed into the larger, collective body of commentary that was passed down through centuries. Later lexicographers, such as Hesychius of Alexandria, found his explanations of rare Homeric words useful enough to record, ensuring his work left a trace in the history of classical scholarship.