The original trilogy's final instalment, Mass Effect 3 (2012), depicts a war between the Reapers and the rest of the galaxy. Mass Effect 2 (2010) begins two years later and sees Shepard's forces battling the Collectors, an alien race abducting human colonies to facilitate the Reapers' return. The inaugural video game in the series, Mass Effect (2007), follows Shepard's investigation of Saren Arterius, one of the Reapers' agents. The first three games form a trilogy in which the player character, Commander Shepard, attempts to save the galaxy from a race of ancient, hibernating machines known as the Reapers. Each installment is a third-person shooter with role-playing elements. The franchise originated in a series of video games developed by BioWare and published by Electronic Arts.

The franchise depicts an alternate universe where humanity and several alien civilizations have colonized the Milky Way galaxy using technology seemingly left behind by an advanced precursor civilization. Mass Effect is a science fiction media franchise created by Casey Hudson, Drew Karpyshyn and Preston Watamaniuk.