Events that occurred on 18 September.
 On Earth
- 1905 - Author George MacDonald dies.
- 1954 - J.R.R. Tolkien writes letters 150 and 151.
- 1954 - Naomi Mitchison published a review of The Fellowship of the Ring in the New Statesman.
- 1955 - Voice actor Bob Papenbrook is born.
- 1963 - Writer Gary Russell is born.
- 1967 - J.R.R. Tolkien writes a letter to Elsie Honeybourne.
- 1981 - Extracts from J.R.R. Tolkien's "The Name Coventry" is published in The Catholic Herald.
- 1982 - The tenth episode of the new version of the 1981 radio series of The Lord of the Rings is aired on BBC Radio 4.
- 1993 - Oxonmoot 1993 at University College.
- 1994 - Oxonmoot 1994 at University College.
- 2003 - Oxonmoot 2003 at St Hugh's College.
- 2004 - Oxonmoot 2004 at St Hilda's College.
- 2004 - The Lord of the Rings Symphony at Mortensen Hall in Hartford, Connecticut.
- 2005 - Oxonmoot 2005 at St Peter's College.
- 2006 - The Children of Húrin is announced.
- 2020 - Oxonmoot 2020 held online due to the Covid-19 pandemic.
 In Arda
- T.A. 3018: