There are now three major groups of gatekeepers. Mass media gatekeepers are those traditionally thought of as selecting, shaping and publishing news content, with primarily unidirectional communication from the media organization to an audience. Social media gatekeepers (users) are the individuals and organizations that create and publish the content housed on social media conglomerates' servers. These conglomerates not only own and manage the content of social media users, but also publish their own news services. This essay proposes that these conglomerates are gatekeepers because select and publish content from social media users and from the mass media. The many interactions among agents of these three groups create a complex gatekeeping system that should be theoretically analyzed through a systematic or holistic approach.