Meaning: tender of beasts
Other Names: Aiwendil (Q)
Location(s): Valinor; Rhosgobel, near the borders of Mirkwood
Title(s): the Brown
"For Radagast, the fourth, became enamoured of the many beasts and birds that dwelt in Middle-earth, and forsook Elves and Men, and spent his days among the wild creatures."
Unfinished Tales, Part Four, II - The Istari
This Istar is known as Radagast (in the Númenórean speech) among Men and Aiwendil (Quenya) among Elves. Aiwendil means 'lover of birds'.
Radagast appeared to have inadverdantly aided Saruman during the latter's search for the Ring. "He [Saruman] gathered a great host of spies, and many of these were birds; for Radagast lent him aid, divining naught of his treachery, and deeming that this was but part of the watch upon the Enemy."
The Silmarillion, Of the Rings of Power
"Radagast is, of course, a worthy Wizard, a master of shapes and changes of hue; and he has much lore of herbs and beasts, and birds are especially his friends."
LotR, FotR, Book Two, II - The Council of Elrond
Ying, 01.12.03; Loquacious 01.10.03