Events that occurred on 23 January.
 On Earth
- 1917 - J.R.R. Tolkien faces a Medical Board in Birmingham, but he is not deemed fit to return to war.
- 1939 - The Brothers Hildebrandt are born.
- 2020 - Barbara Remington, cover artist on some American editions, dies.
- 2021 - Tolkien and the Classical World is published.