It is up for debate whether or not Radagast succeeded in his mission as one of the five Wizards, but answers can be found in the books.

The Elvish languages were the first thing he imagined for his secondary world of the Middle-Earth. The writer said that his classic fantasy works, The Hobbit and The Lord of the Rings, grew out of ...

Gildor Inglorion was absent from Peter Jackson's film adaptations of The Lord of the Rings, but one scene from the extended editions referenced him.