Mikhail Sergeyevich Cossack is a robotics engineer and scientist and a character from the Mega Man series. He is the foremost expert on robotics in Russia and is a friend and colleague of Dr. Thomas Light. This was not always the case, however. When he first appeared in Mega Man 4, Dr. Cossack threatened to conquer the world using his eight new Robot Masters and sent them after Mega Man. Mega Man was able to defeat them and confronted Dr. Cossack in his Siberian castle. Before Mega Man could finish off the Cossack Catcher, Proto Man appeared with Dr. Cossack's daughter Kalinka. It was revealed that Kalinka had been abducted by Mega Man's old foe Dr. Wily who had blackmailed Cossack into attacking Mega Man, but Proto Man betrayed Wily and rescued Kalinka.
Ever since Mega Man 4, Dr. Cossack has been an ally of Mega Man and has occasionally helped the Blue Bomber by providing support units and upgrades for him. He is the creator of Beat, a pet bird robot who was given to Mega Man as a gift for rescuing Kalinka.