Events that occurred on 13 April.
 On Earth
- 1902 - Voice actor Godfrey Kenton is born.
- 1937 - J.R.R. Tolkien writes Letter 12.
- 1944 - J.R.R. Tolkien writes Letter 60.
- 1970 - Tom Shippey receives a letter from J.R.R. Tolkien after giving a speech at a Tolkien-themed convention.
- 2000 - Another edition of Tolkien: The Illustrated Encyclopedia is published.
- 2005 - German translator Wolfgang Krege dies.