Events that occurred on 27 October.
 On Earth
- 1916 – J.R.R. Tolkien is struck by trench fever, which ends his contribution to the war after just 5 months.
- 1938 - Lascelles Abercrombie dies.
- 1943 - J.R.R. Tolkien writes Letter 51.
- 1968 - Barrels out of Bond, the fifth episode of the 1968 radio series of The Hobbit, is aired on BBC Radio.
- 1983 - The Book of Lost Tales Part One is published in the UK.
- 1992 - Sauron Defeated is published in the US.
- 1992 - Pictures by J.R.R. Tolkien (revised edition) is published.
- 1995 - J.R.R. Tolkien: Artist and Illustrator is published.
- 2005 - Tolkien's Modern Middle Ages is published.
- 2009 - Fantasy novel The Shadow Dragons, featuring J.R.R. Tolkien as a fictional character, is published.
- 2011 - A revised updated single-edition version of The History of The Hobbit is published.
- 2011 - The Art of The Hobbit is published.