Valmiki (Sanskrit: वाल्मीकि, romanized: Vālmīki) was a legendary poet celebrated as the traditional author of the epic Ramayana, based on the attribution in the text itself. He is revered as Ādi Kavi, the first poet, and the author of the Ramayana, the first epic poem.

The Ramayana, originally written by Valmiki, consists of 24,000 shlokas and seven cantos (kaṇḍas). The Ramayana is composed of about 480,002 words, being a quarter of the length of the full text of the Mahabharata or about four times the length of the Iliad. The Ramayana tells the story of a prince, Rama of the city of Ayodhya in the Kingdom of Kosala, whose wife Sita is abducted by Ravana, the demon-king (Rakshasa) of Lanka.

Scholars estimate the earliest stage of the text ranges from the 8th to the 4th centuries BCE, with later stages extending up to the 3rd century CE, although the original date of composition is unknown. As with many traditional epics, it has undergone a process of interpolations and redactions, making it impossible to date accurately.

British satirist Aubrey Menen says that Valmiki was "recognized as a literary genius," and thus was considered "an outlaw," presumably because of his "philosophic scepticism," as part of an "Indian Enlightenment" period. Valmiki is also quoted as being the contemporary of Rama. Menen claims Valmiki is "the first author in all history to bring himself into his own composition."

Valmiki is celebrated as the poet harbinger in Sanskrit literature. The Yoga Vasistha is also attributed to him. A religious movement called Valmikism is based on Valmiki's teachings as presented in the Ramayana and the Yoga Vasistha.

At least by the 1st century AD, Valmiki's reputation as the father of Sanskrit classical poetry seems to have been legendary. Ashvagosha writes in the Buddhacarita, "The voice of Valmiki uttered poetry which the great seer Chyavana could not compose."