Tolkien has a special interest in Old English, Old Norse and historic verse and taught classes on all these topics throughout his career. His lecture on Beowulf, entitled "Beowulf: The Monsters and the Critics" is considered a formative work on modern Beowulf studies. An excerpt from the work is copied below.

“It is just because the main foes in Beowulf are inhuman that the story is larger and more significant than this imaginary poem of a great king's fall. It glimpses the cosmic and moves with the thought of all men concerning the fate of human life and efforts; it stands amid but above the petty wars of princes, and surpasses the dates and limits of historical periods, however important. At the beginning, and during its process, and most of all at the end, we look down as if from a visionary height upon the house of man in the valley of the world. A light starts—lixte se leoma ofer landa fela—and there is a sound of music; but the outer darkness and its hostile offspring lie ever in wait for the torches to fail and the voices to cease.”

J.R.R. Tolkien, "Beowulf: The Monsters and the Critics", 1936.

The epic influenced Tolkien’s fiction works as well, as he comments on in one of his letters.

As for the rest of the [Hobbit] it is … derived from (previously digested) epic, mythology, and fairy-story … Beowulf is among my most valued sources.

J.R.R. Tolkien, Letter 25.

Grímur Jónsson Thorkelín. The Thorkelin Transcripts of Beowulf in Facsimile. Ed.

by Kemp Malone. Copenhagen: Rosenkilde and Bagger, 1951.

This transcription of the original Beowulf manuscript (presented here in facsimile) was done by Grima Thorkelin on a trip to England in 1786. Thorkelin is the first person to make a full translation of the poem, which he rendered in German and Latin. As the original Beowulf manuscript continued to deteriorate, Thorkelin’s transcription preserved pieces of the text which would have otherwise been lost forever. Not only did he make his own translation, his work preserved the text for future translators, such as Tolkien, who worked on his Beowulf translation from 1920-1926, and which was published posthumously by Christopher in 2014.

Click here to see pages from the orignal Beowulf manuscript, made avaible by the British Library.