Events that occurred on 18 April.
 On Earth
- 1917 - J.R.R. Tolkien and Christopher Wiseman, the Great Twin Brethren, meet in Harrogate, and discuss the fate of the Barrovians and the future of the Society.
- 1930 - Voice actor Clive Revill is born.
- 1944 - J.R.R. Tolkien writes Letter 61.
- 1945 - Amateur cartographer Karen Wynn Fonstad is born.
- 1955 - J.R.R. Tolkien writes Letter 162.
- 1963 - J.R.R. Tolkien starts writing a letter to Mr. and Mrs. Kloos.
- 1984 - Voice actor Francis de Wolff dies.
- 2007 - The fourth and final day of The Children of Húrin Release Party is hosted by Tolkien Gateway.
 In Arda
- There are no known events for this day.