Ecumene

The Ecumene was a massive galaxy-spanning empire controlled and created by the Forerunner people in the Halo Universe. It was set up as a secure Imperialistic government in an attempt to honor the Forerunner's creators, the Precursors. However, this ideal was soon lost after the Ecumene waged war against the Precursors and committed genocide toward their race. Years later, after a massive conflict against the Human-San'Shyuum Alliance, the Ecumene would be destroyed after the rise of The Flood parasite engulfed the entire galaxy. The remnant forces of the Ecumene than worked to destroy the massive threat of The Flood by creating the Halo rings and using them to kill off the entire Flood threat, as well as recreating the various species of life that The Flood had previously destroyed.