Introduction
Jambavan is the king of the bears (Riksha) and the oldest and wisest advisor of Rama's army. In Valmiki he was born from the yawn of Brahma, at the beginning of creation.
This article primarily follows the Valmiki Ramayana. Where a well-known detail comes from a later retelling or tradition, the article identifies it.
The counsellor
Jambavan is the elder of the group. When the Vanaras stood at the seashore, unable to cross, he could not make the leap himself because of his age. He reminded Hanuman of his own powers, and Hanuman then grew and leapt across the ocean to Lanka.
In the war
When Lakshmana fell, Jambavan told Hanuman to fetch healing herbs from the Himalayas, and named the mountains where they grew. He also took part in the fighting, even at his great age.