J.R.R. Tolkien wrote an essay entitled "Beowulf: The Monsters and the Critics". He used it for a lecture in 1936.
He viewed Beowulf as an important literary document. He said that it is a poem. Its theme is about mortality and it is divided into two parts. The first part is about Beowulf as a young man and his victory against Grendel and his mother. The second part is about Beowulf as an old man and his death as he fought the dragon.