A resposta está na Wikipedia:
Ronan was born on the planet Hala, the capital of the Kree Empire in the Greater Magellanic Cloud. Ronan later joined the Accuser Corps, who are the Kree equivalent of military governors and jurists, and his rise through their ranks was extraordinary; he eventually became the third-most powerful being in the Kree Empire. The Supreme Intelligence ultimately appointed him "Supreme Accuser of the Kree Empire", as which he is known simply as "Ronan the Accuser".