Radagast is not a large part of The Lord of the Rings, so it makes sense that Tolkien wouldn't explore the character's fate ...

In The Lord of the Rings, there are five main wizards who ... Saruman's power during the period that Theoden was under the White Wizard's influence, there's likely a reason that Saruman selected ...

Throughout Tolkien's Middle-earth, in The Lord of the Rings ... of Durin's Tower, and Gandalf killed the Balrog. While Gandalf the Grey died, he was resurrected as Gandalf the White.

Their destinies lie at two towers--Orthanc Tower in Isengard, where the corrupt wizard Saruman awaits, and Sauron's fortress at Barad-dur, deep within the dark lands of Mordor.