Dr.Wily is the evil mastermind behind all the megaman games. I think he is pretty stupid, but i geuss he is needed to complete the storyline of the games.
Protoman is tha main bad guy throughout all of the Megaman games up until the X series.
Here are some various bosses throughout all the games.
Here is the Maverick, Vile , and this is a picture from X3.
Here's a picture of Dr.Doppler
Here's a picture of bit, from the X series. Here's a picture of Byte.
Here are some of the crap bots