Sir Orfeo is a 1944 booklet which reproduces the text of the Middle English poem as edited and amended by J.R.R. Tolkien, together with an editorial note also by Tolkien. Tolkien's translation of it was later published in Sir Gawain and the Green Knight, Pearl and Sir Orfeo.

Although the booklet does not identify Tolkien's editorship, a copy held by the Bodleian Library in Oxford includes a note in Tolkien's hand which states that it was prepared for a naval cadets' course in English that ran from 1943-1944.

The number of copies printed is unknown, but was probably small. In his J.R.R. Tolkien: A Descriptive Bibliography, Wayne G. Hammond reported that "Five copies have been located." The lack of known copies of Sir Orfeo may be due in part to the fact that Tolkien is not recorded as editor, making it unlikely that many booksellers would identify the Tolkien connection.[1]

The poem is a Celtic retelling of the Ancient Greek myth of Orpheus, King of Thrace, who went to the Underworld (here the Otherworld) to save his wife Eurydice (Heurodis) from Hades (Fairy King).

In 2004, the text of the 1944 Sir Orfeo was reprinted in Tolkien Studies: Volume 1, edited by Carl F. Hostetter.

A musical rendition of the Middle English text: https://youtu.be/eaEiu10DS_4

A reading of the Middle English text: https://youtu.be/kllYoonQFXI