September 21 is the 264th day of the year (265th in leap years). There are 101 days remaining.
- 1964 – Jim Marquand is born.
- 1985 – "Rampage of the Phlogs" and "The Trigon Unleashed" aired on ABC.
- 2004 – The original trilogy is released on DVD.
- 2005 – Empire 36: The Wrong Side of the War, Part 1 published.
- 2011 – Jedi—The Dark Side 5 published.
- 2011 – Knight Errant: Deluge 2 published.
- 2011 – Star Wars Omnibus: The Complete Saga published.
- 2018 – Star Wars: The Empire Strikes Back Manga published.