Valmiki is celebrated as the harbinger-poet in Sanskrit literature. The epic Ramayana, dated variously from the 5th century BCE to first century BCE, is attributed to him, based on the attribution in the text itself. He is revered as Ādi Kavi, the first poet, author of Ramayana, the first epic poem.

How did Valmiki become Rishi?
As he performed his penance for several years, the word became "Rama", the name of Lord Vishnu. Huge anthills formed around Agni Sharma and this earned him the name of Valmiki. ... There also exist some legends about Valmiki having been a thief before turning into a rishi.