In the poem , Beowulf fights three monsters : Grendel and Grendel 's mother , and later in his life an unnamed dragon . Jane Chance ( Professor of English , Rice University ) in her 1980 article `` The Structural Unity of Beowulf : The Problem of Grendel 's Mother '' argued that there are two standard interpretations of the poem : one view which suggests a two-part structure ( i.e. , the poem is divided between Beowulf 's battles with Grendel and with the dragon ) and the other , a three-part structure ( this interpretation argues that Beowulf 's battle with Grendel 's mother is structurally separate from his battle with Grendel ) .