Events that occurred on 21 August
 On Earth
- 1957 - Artist John Howe is born.
- 1961 - An interview with J.R.R. Tolkien ("Den besynnerlige professor Tolkien") is published in Swedish.
- 1982 - The sixth episode of the new version of the 1981 radio series of The Lord of the Rings is aired on BBC Radio 4.
- 1986 - The Shaping of Middle-earth is published in the UK.
- 1992 - Tolkien Centenary Conference, a combination of Oxonmoot 1992 and Mythcon XXIII, at Keble College, Oxford.
- 2000 - Mythcon XXXI in Hawaii.
- 2006 - The Oxford Tolkien Conference at Exeter College, Oxford.
- 2007 - The tenth book of The Lord of the Rings Online: Shadows of Angmar, The Hidden Hope, is released in North America.