Events that occurred on 23 September.
 On Earth
- 1930 - J.R.R. Tolkien completes a manuscript of The Lay of Aotrou and Itroun
- 1944 - J.R.R. Tolkien starts writing Letter 81.
- 1960 - Voice actor Jason Carter is born.
- 1977 - Oxonmoot 1977 at The Welsh Poney.
- 1978 - Oxonmoot 1978 at Oxford Town Hall.
- 1983 - Oxonmoot 1983 at Oxford Town Hall.
- 1988 - Oxonmoot 1988 at Oxford Town Hall.
- 1989 - Oxonmoot 1989 at Oxford Town Hall.
- 1990 - Oxonmoot 1990 at Oxford Town Hall.
- 1993 - Morgoth's Ring is published in the UK.
- 2000 - Oxonmoot 2000 at St Antony's College.
- 2001 - Oxonmoot 2001 at St Antony's College.
- 2004 - There and Back Again: An Actor's Tale is published.
- 2011 - Oxonmoot 2011 at Lady Margaret Hall.
- 2012 - Oxonmoot 2012 at Lady Margaret Hall.
- 2016 - Actor William Johnson dies.
- 2017 - Oxonmoot 2017 at St Antony's College.
- 2018 - Oxonmoot 2018 at St Antony's College.
- 2019 - "Something Has Gone Crack" is published.
 In Arda
- T.A. 3001:
- T.A. 3018:
- Four Riders enter the Shire before dawn. The others pursue the Rangers eastward, and then return to watch the Greenway.
- A Black Rider comes to Hobbiton at nightfall.
- Bag End passes to Lobelia Sackville-Baggins and Frodo leaves for Crickhollow with Sam and Pippin.
- After taming Shadowfax, Gandalf leaves Rohan and heads for Rivendell.
- Boromir travels towards Rivendell to ask for counsel.