Beowulf is an Anglo-Saxon epic translated, among others, by J.R.R. Tolkien himself.
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 ..."
Tolkien and Beowulf - Michael Kennedy details some of the similarities between the two.