Events that occurred on 12 April.
 On Earth
- 1958 - Voice actor Tony Oliver is born.
- 1962 - J.R.R. Tolkien writes Letter 237.
- 1966 - J.R.R. Tolkien writes a letter to Mother Mary Anthony.
- 1966 - J.R.R. Tolkien writes a letter to James Ridolfo.
- 1981 - The sixth episode of the 1981 radio series of The Lord of the Rings is aired on BBC Radio 4.