The most difficult to describe of the poem's characters, he assumes many different shapes and guises. At times the Narrator seems to be Eliot himself; at other times he stands in for all humanity. In "The Fire Sermon" he is at one point the Fisher King of the Grail legend, at another the blind prophet Tiresias. When he seems to reflect Eliot, the extent to which his ruminations are autobiographical is ambiguous.
For an indepth look at the character and personas in the text, read through GradeSaver's study guide, which is readily avaiable for your use.