Who is the main antagonist of the classic Mega Man series?

The main antagonist of the classic Mega Man series is Dr. Wily.

Dr. Albert W. Wily was originally Dr. Light’s university colleague. Jealous of Light’s achievements, Wily reprogrammed Light’s industrial robots and used them in an attempt to conquer the world. Light’s assistant robot, Rock, was upgraded into Mega Man and defeated him.

Wily repeatedly returns in the classic games with new Robot Masters, fortresses, and schemes. Although he is usually defeated and often begs for mercy, his persistence is one of the series’ defining running jokes. His role is different from Sigma’s: Sigma is the principal villain of the later Mega Man X series, while Wily is the recurring villain of the original classic timeline.

Wily’s influence extends beyond his own games. He created Proto Man’s original prototype and later created Bass and Zero, linking his legacy to later eras of the franchise.