The Fourth Generation
The Oolu are from planet Olo. One of the most advanced races in the galaxy they took to exploring other worlds peacefully and not getting involved. One world was on environmental collapse due harm caused by the inhabitants. The Oolu just watched the planet and people die.
After that the Oolu decided they would assist planets that would harm themselves. They first offered their assistance but found their help was not wanted. Other planets and its inhabitants were destroying themselves.
The Oolu decided they could no longer let this happen. They would send representatives of planets to judge if they could govern themselves and if the race is developing with their environment and would benefit the galaxy. If not they would invade the world and force the people to conform to their orthodoxy.