Letter to Michael George Tolkien (29 July 1966)
- Publication: The letter was partly published in The Letters of J.R.R. Tolkien as Letter 289. The bulk of the letter was published in The Lord of the Rings: A Reader's Companion: "Prologue, 3 (I: 12). Mirkwood".
- Note: The letter is kept at the British Library (MS Add. 71657).
[Before the following excerpt, the first paragraph of letter 289 is found. After the excerpt, the second paragraph of letter 289 follows].
"In O[ld] N[orse], myrkviðr is often found, mainly in Eddaic verse as a proper name. The best known examples are Völundarkviða 'Lay of Wayland' line 2 where swanmaidens are said to fly from the south through Mirkwood (meyjar flugu sunnan Myrkvið ígegnum). The legend and the lay are not of ultimately Norse origin, but derived from the area whence the English came. No doubt *Mircwudu would have appeared in it. The other is in Atlakviða ['Lay of Atli'], the long and corrupt lay dealing with the way in which Atli (Ætla, Attila) got the brothers of Guðrún to come and visit him and then murdered them. Among the many gifts and territories that he promised to give them in stanza 5 is mentioned hrís þat et mæera es menn Myrkvið kalla 'that renowned forest that men call Mirkwood'."
 See also
- Letter to Michael George Tolkien (24 April 1957)
- Letter to Michael George Tolkien (10 January 1958)
- Letter to Michael George Tolkien (6 January 1965)
- Letter to Michael George Tolkien (16 September 1965)
- Letter to Michael George Tolkien (30 October 1965)
- Letter to Michael George Tolkien (7 January 1970)
- Letter to Michael George Tolkien (30 January 1972)