Events that occurred on 5 September.
 On Earth
- 1970 – The first Mythcon is held at Harvey Mudd College in Claremont, California.
- 1971 - Mythcon 2 in Santa Barbara, California.
- 1975 - Oxonmoot 1975 at the Welsh Poney, Oxford.
- 2000 - Tyalië Tyelelliéva issue 15 is published.
- 2005 - A version of Smith of Wootton Major is released, edited by Verlyn Flieger.
- 2019 - Tolkien Calendar 2020 is published.