Junkman

Original background story
Junkman was once a Crash Dummy, but he had a few screws loose. Maybe he took too many head-ons without a safety belt! "Why should I crash cars to help humans?" he asked. "Who needs humans? Machines should rule the world!" Fired from the Crash Test Center, Junkman hid out in an abandoned junkyard. Using old car parts, he rebuilt himself into a powerful robot. Then he created his Junkbot army and began plotting his revenge.

"I don't hate all Crash Dummies," says Junkman, "only the ones I haven't made into Junkbots yet!"

History
Junkman was the leader of the Junkbots and arrived on the scene in 1992, forcing the Crash Dummies to switch their jumpsuits to Pro-Tek. He and his 'bots were a unique blend of human-like arms and legs and mechanical junkyard parts. Junkman's head and arms could be removed but no button released anything. Instead, he came with a special cannon that could hypothetically trigger a Dummy's button if it hit it right.

Trivia

 * Coincidentally, there is a Robot Master in Mega Man 7 also called Junk Man.