This is a timeline for significant events about the game. This is for real life dates and events, not the In-game timeline.
- 04/27/2004 - City of Heroes released
- 06/29/2004 - Issue 1 released
- 08/30/2004 - Film Festival contest began
- 09/16/2004 - Issue 2 released
- 09/16/2004 - Rularuu Invasion Event 2004
- 09/28/2004 - First Halloween Costume contest began
- 10/??/2004 - Halloween Event 2004
- 11/09/2004 - Collector's Edition (City of Heroes) released
- 01/04/2005 - Issue 3 released
- 01/12/2005 - Winter Event 2004 began
- 02/05/2005 - City of Heroes released in Europe
- 02/08/2005 - Winter Event 2004 ended
- 04/14/2005 - Thursday Throwdown
- 04/20/2005 - Wednesday Night Fights
- 05/04/2005 - Issue 4 released
- 05/01/2005 - First Anniversary event
- 08/31/2005 - Issue 5 released
- 10/27/2005 - Issue 6 released
- 10/31/2005 - City of Villains released
- 12/08/2005 - Winter Event 2005 began
- 01/02/2006 - Winter Event 2005 ended
- 01/18/2006 - City of Heroes open beta begins in Korea
- 02/08/2006 - Valentine's Day Event 2006 began
- 04/01/2006 - Second Anniversary Events
- 06/06/2006 - Issue 7 released
- 07/21/2006 - Double XP weekend (Ended 07/23/2006)
- 09/01/2006 - Cuppathon was held on the test server
- 09/29/2006 - Good Versus Evil Edition released
- 10/18/2006 - Halloween Event 2006 began
- 10/31/2006 - Halloween party on test server
- 11/02/2006 - Halloween Event 2006 ended
- 11/02/2006 - City of Villains First Anniversary event began
- 11/28/2006 - Issue 8 released
- 11/30/2006 - City of Villains First Anniversary event ended
- 12/14/2006 - Winter Event 2006 began
- 01/02/2007 - Winter Event 2006 ended
- 01/08/2007 - Winter Event 2006 returned
- 01/17/2007 - Winter Event 2006 ended for the 2nd time
- 01/26/2007 - Double XP weekend (ended 01/28/2007)
- 02/13/2007 - Valentine's Day Event 2007 began
- 03/04/2007 - Valentine's Day Event 2007 ended
- 04/27/2007 - Third Anniversary Event on Test server
- 05/01/2007 - Issue 9 released
- 06/15/2007 - Double XP weekend (Ended 06/17/2007)
- 07/24/2007 - Issue 10 released
- 07/24/2007 - Rikti World Invasion began
- 08/07/2007 - Daily Rikti World Invasion ended
- 08/14/2007 - Rikti Invasion Encore (24 hour Invasion)
- 08/18/2007 - Rikti Invasion Encore
- 08/23/2007 - Rikti Invasion Encore
- 08/26/2007 - Rikti Invasion Encore
- 08/31/2007 - Rikti Invasion Encore
- 09/02/2007 - Rikti Invasion Encore
- 09/12/2007 - Rikti Invasion Encore
- 09/15/2007 - Rikti Invasion Encore
- 09/17/2007 - Rikti Invasion Encore
- 09/22/2007 - Rikti Invasion Encore
- 10/22/2007 - Halloween Event 2007 began
- 11/04/2007 - Halloween Event 2007 ended
- 11/28/2007 - Issue 11 released
- 12/17/2007 - Winter Event 2007 began
- 01/06/2008 - Winter Event 2007 ended
- 02/08/2008 - Double XP Weekend start (Ended 02/10/2008)
- 02/14/2008 - Valentine's Day Event 2008 began
- 02/28/2008 - Valentine's Day Event 2008 ended
- 03/07/2008 - Rikti Invasion Returns (Ended 03/14/2008)
- 04/18/2008 - Rikti Invasion Returns (Ended 04/24/2008)
- 06/13/2008 - Rikti Invasion Returns (Ended 06/19/2008)
- 08/01/2008 - Rikti Invasion Returns (Ended 08/07/2008)
- 09/26/2008 - Rikti Invasion Returns (Ended 10/02/2008)
- 11/14/2008 - Rikti Invasion Returns (Ended 11/20/2008)