An incarnate maia, one of five Istari, or Wizards, sent by the Valar in the Third Age to advise and encourage the Free Peoples of Middle-Earth. He arrived at the Grey Havens c TA 1000 and made his home on the edge of Mirkwood where he devoted himself to birds and beasts and the world of nature. It is not known whether he returned to the West after the War of the Ring.

Radagast is first mentioned in The Hobbit where Gandalf refers to him as his cousin and says that he lives on the southern border of Mirkwood. The word cousin is used here in its archaic sense meaning, a fellow member of a group.

Radagast was also called the Brown Wizard. In Valinor he was called 'Aiwendil' meaning 'Lover of Birds' in Quenya. Saruman called him by many mocking titles, including 'The Bird Tamer' 'The Simple' and 'The Fool'.

He was sent to Middle-earth by the Vala Yavanna as a companion for Curumo (Saruman).

He loved the birds and beasts of Middle-earth so much that he forsook Elves and Men and spent his time among the animals. That is how he got the name Radagast, in the language of Númenór it means 'tender of beasts'

He lived at Rhosgobel, his house on the borders of Mirkwood.

He played some inadvertant parts in the War of the Ring: He helped Saruman to spy by lending him help with the birds, but did not know of Saruman's treachery, and thought he was spying on Sauron.

He was part of Saruman's ploy to get Gandalf to Orthanc. Saruman sent Radagast out to look for Gandalf with the message that he would help. But as Radagast did not realize Saruman's treachery, he saw no reason not to do as Saruman had told him, and send any news to Orthanc. He sent Gwaihir the great eagle, who found Gandalf imprisoned on the pinnacle of Orthanc. He then carried Gandalf away to Rohan.