Events that occurred on 23 October.
 On Earth
- 1923 - Bulletin of the Modern Humanities Research Association 20, containing an obituary written by J.R.R. Tolkien, is published.
- 1937 - J.R.R. Tolkien writes Letter 18.
- 1944 - J.R.R. Tolkien writes Letter 86.
- 1999 - Hiswelókë's Sindarin dictionary begins.
- 2008 - The Spoken Word: British Writers, featuring an interview with J.R.R. Tolkien, is released.