The Anglo-Saxon epic J.R.R. Tolkien studied and translated extensively was Beowulf.
Beowulf is an Old English poem about a hero who fights the monster Grendel, Grendel's mother, and, later in life, a dragon. Tolkien was a leading scholar of Old English and delivered his influential lecture “Beowulf: The Monsters and the Critics” in 1936.
His scholarly work helped change the way the poem was studied. Instead of treating its monsters as distractions from historical material, Tolkien argued that they were central to the poem's structure and meaning. His interest in heroic literature, dragons, languages, and northern myth also informed his creative writing.
Tolkien translated Beowulf into modern English, but that translation was published posthumously in 2014, edited by his son Christopher. The poem itself remains anonymous; Tolkien was its scholar and translator, not its author.