Beowulf (poem)
From Tolkien Gateway
J.R.R. Tolkien looked highly upon Beowulf, and derived many ideas and translations from the myth. In The Letters of J.R.R. Tolkien #25 the Professor states, "Beowulf is among my most valued sources ..."
External Links
[Tolkien and Beowulf] - Michael Kennedy details some of the similarities between the two.