There are about three bands with the name "Rex Mundi." Or King of the World, translated in Latin. 1. Dj/Producer Rex Mundi 2. French Black Metal act (Technically spelled Rêx Mündi) 3. Thrash/Progressive band from Greece 1. Dj Rex Mundi Boy Hagemann started producing music on his computer while his friends practiced in local rock bands. He was fascinated about the sounds that could be created using just a computer, He sometimes skipped college to have fun with his music.