Radagast the Brown is a wizard in J. R. R. Tolkien's fantasy epic The Lord of the Rings and mentioned in The Hobbit. He was a good friend of Gandalf, and had a strong affinity for animals.

Warning: Wikipedia contains spoilers

Radagast was unwittingly used by Saruman to lure Gandalf to Orthanc, where Gandalf was captured.

Tolkien did not write that Radagast returned to Aman as Gandalf did.