Introduction
Viradha is a Rakshasa who attacked Rama, Sita and Lakshmana in the Dandaka forest. He was killed by them, and released from a curse.
This article primarily follows the Valmiki Ramayana. Where a well-known detail comes from a later retelling or tradition, the article identifies it.
The attack
Viradha seized Sita and tried to carry her off. Rama and Lakshmana cut off his arms, but he could not be killed by weapons, so they buried him alive. As he died, he said that he was really the celestial being Tumburu, cursed by Kubera to be born as a Rakshasa.
Directions
He told them to seek out the sage Sharabhanga.