Duo.EXE

A massive, mysterious alien NetNavi who is alluded to in the second half of Rockman.EXE Axess and appears in the next season as the main overall antagonist. It is eventually revealed that he was created on Earth in the distant past by an ancient civilization who felt their network was going down a dark path and Duo.EXE was made to maintain it, and was launched into space, his rocket becoming a “comet” (dubbed “Duo’s Comet”) that only those marked with his "Crest" could see. Evolving from his original purpose and seeing his creators and their civilization as evil, Duo.EXE eradicated all life on Earth from that time, becoming a “Cybernetic god” that travels the cosmos, analyzing and testing planets and civilizations to see if they are worthy, and destroying those he deems are not.

(Source: The Mega Man Knowledge Base)