Observer

The main check on each of the empires it has agents, called Empire Hunters, in each empire which monitor and look out for any they believe can have dangerous affects on other empires. Given a large amount of power in each nation but not the power to actively infringe upon another nations governance and people. However any uncooperative empire is flagged for investigation as it must be hiding something.  Most of its agents work in secret so as not to alert the nations of the Observers presents.  

Observer

Observer Kindal