Introduced in the first "Mega Man" game, Wily was an old friend of Dr. Light, whose achievements in designing several advanced robots (including intelligent humanlike robots) overshadowed Wily's own accomplishments. Jealous, he reprogrammed the robots for combat, seeking to use them as weapons to assist him in taking over the world, with the exception of the childlike robots Rock and Roll. However, he was defeated by Rock, now converted into the combat robot "Mega Man". Wily returned as the antagonist of subsequent titles in the main series with a different scheme each time, sometimes framing someone else for his crimes (Dr. Cossack, Proto Man, a disguise for himself named Mr. X, and Dr. Light), only to be defeated and surrender to Mega Man at the end. Wily is also responsible for the creation of several other characters throughout the series, including Bass and Zero, and is indirectly responsible for the behaviour of the antagonist of the "Mega Man X" series, Sigma, during that series.