Events that occurred on 13 December.
 On Earth
- 1907 - Translator Ebba-Margareta von Freymann is born.
- 1937 - Arthur Ransome writes a letter to J.R.R. Tolkien.
- 1954 - J.R.R. Tolkien writes a letter to Rayner Heppenstall.
- 1967 - Margaret Carroux comes to meet J.R.R. Tolkien in Oxford to talk about her German translation.
- 1972 - J.R.R. Tolkien writes Letter 346.
- 2012 - The Hobbit: An Unexpected Journey is released in Europe.
- 2013 - The Hobbit: The Desolation of Smaug is released.
- 2013 - The Hobbit: The Desolation of Smaug: Chronicles: Art & Design is published.
- 2015 - Author Daniel Grotta dies.