The Grey Wizard was perhaps best known to Men as Gandalf, or to the Elves as Mithrandir, but neither of these were his true name: he was a Maia out of the West, where his original name was said to have been Olórin. While in Middle-earth, apart from his common names of Gandalf or Mithrandir, he gained many different names among different peoples, and among these was Incánus.

There are various interpretations and analyses explaining the etymology behind the name Incánus.² The two main interpretations are based on two different languages, with Incánus coming either from the language of the Haradrim, or from the Quenya tongue used by the scholars of Gondor.

The earlier of these suggestions places Gandalf in the southern land of the Harad during the early part of his time in Middle-earth. During this period, the Harad was under the power of Gondor, and so would have been rather more accessible than it later became. According to this tradition, Gandalf travelled there often enough to acquire a name among its people. In the language of the Haradrim, inká meant 'north' and nûs meant 'spy'. Rendering these words in an Elvish style gave rise to Incánus, meaning 'North-spy'.

This approach was later revised, and Tolkien came to think that Gandalf had not in fact visited the Harad, or at least not for long enough to acquire a unique name there. According to this later view, when Gandalf said that he was known as Incánus in the South, he was instead referring to Gondor. He was most commonly called Mithrandir there, but Incánus was a name given him in Quenya by the loremasters of that land.

By this interpretation, the name derived from Elvish elements meaning 'mind' and 'ruler', so the full name would be translated as something like 'learned lord'. It was in use especially in the time when Gondor was at the height of its power, in about the period when Atanatar II Alcarin was King (that is, about 1,800 years before the War of the Ring). By the end of the Third Age, this scholarly name for Gandalf had long fallen out of use in Gondor, though Gandalf himself evidently remembered it.