Events that occurred on 17 September.
On Earth
- 1928 – Voice actor Roddy McDowall is born.
- 1937 - J.R.R. Tolkien writes Letter 15a.
- 1945 – Actor Bruce Spence is born.
- 1972 – J.R.R. Tolkien writes Letter 341.
- 1993 – Oxonmoot 1993 at University College.
- 1994 – Oxonmoot 1994 at University College.
- 1995 – Oxonmoot 1995 at University College.
- 2004 – Oxonmoot 2004 at St Hilda's College.
- 2005 – Oxonmoot 2005 at St Peter's College.
- 2006 – Oxonmoot 2006 at Somerville College.