The Old English poem that inspired J.R.R. Tolkien's fictional monsters and heroes is Beowulf.
Beowulf is an Old English epic poem about the hero Beowulf, who fights the monster Grendel, Grendel’s mother, and later a dragon. Tolkien knew the poem deeply and drew on its language, imagery, and heroic patterns when developing his own stories.
His 1936 lecture “Beowulf: The Monsters and the Critics” argued that the poem should be valued as a work of art rather than treated only as historical evidence. The lecture helped change modern academic approaches to Beowulf and remains one of Tolkien’s most important scholarly works.
Tolkien’s fiction does not simply retell the poem. Instead, elements such as dragon-slaying, treasure, heroic reputation, ancient swords, and the tension between courage and mortality appear in transformed ways. The poem’s influence can be felt in The Hobbit especially, but Tolkien’s engagement with Old English literature extended across his career.