Mass Effect is a science fiction video game franchise developed by BioWare. The games are set in a galaxy under attack from a species of mechanical beings known as Reapers who have existed for tens of thousands of years, generally pursuing the extermination of all sentient organic life. Another species, Collectors, are aliens who enslave other species. The Reapers and Collectors, generally, are allied.
The setting has been adapted to several table-top role-playing games.