Mega Man 3 is the third game in the Mega Man Classic series of action platformer games, released in 1990, and is notable for the introductions of Proto Man and Rush, Mega Man's robotic canine companion. Tokuro Fujiwara returned as the producer.
- Mega Man
- Proto Man
- Dr. Wily
- Dr. Light
- Hammer Jacks
- Yellow Devil Mk-II
- Shadow Man
- Top Man
- Quick Man
- Needle Man - is a deadly Robot Master when he uses his weapon Needle Cannon. Created by Dr. Light and Dr. Wily, his initial purpose was to work in energy mines. The spikes on his head can extend to attack from a distance.
- Magnet Man - He fires Magnet Missiles from a launcher on his wrist. He is also equipped with a large magnet, capable of pulling his opponent closer to him, so he can do close-range damage.
- Gemini Man - He is capable of doubling himself, and uses that power to his advantage. Gemini Man is a narcissist, and likes to admire himself in a mirror. He doesn't like snakes, because his weakness is the Search Snake.
- Hard Man - He has a hard, durable exterior made of ceramic titanium, making him rather heavy. Hard Man was originally built for construction work. He can fire his hands, known as Hard Knuckles, and he has a cannon inside of his body. Due to his excessive gravity, he can stomp the ground and cause a tremor, much to Mega Man's dismay.
- Snake Man - is one of the more unusual Robot Masters created by Dr. Wily, and he is decorated as his name suggests, right down to the tail. Snake Man is a very slippery Robot Master that was created to investigate narrow areas.
- Spark Man - is quite an odd Robot Master that was created by Dr. Wily. He does not have arms or hands (like Crash Man, Drill Man or Napalm Man), but in place of them are two high-voltage electrodes called Spark Shock, that are capable of producing powerful electric shocks.
- Kamegoro - turtle-like robots created to investigate the quality of water, but were modified by Dr. Wily to guard the first section of his fortress from intruders. They are released one at a time by a machine, and their speed increases when they lose their shells.
- Doc Robot - is a boss from who has a number of different attachments and devices on his body. He is found at the "revisited" versions of Needle Man's stage, Gemini Man's stage, Spark Man's stage and Shadow Man's stage. He uses the powers of all eight Robot Masters from Mega Man 2 using their program data combined with his specialized devices.
- Gamma - is a giant peacemaker robot constructed by Dr. Light and Dr. Wily, that pretended to be good to obtain help from Light. It is the final boss of the game.
In the year 200X Dr. Wily claims to have reformed and works with Dr. Light on a project to build a peace-keeping robot named "Gamma." However, the eight Robot Masters that the two scientists had designed in order to help maintain peace go berserk, and make off with the eight power crystals. Once again, Mega Man is called into action, but this time with a trusty canine companion named "Rush," to go after them and retrieve the crystals, located on various mining planets in space.
Proto Man, Dr. Light's first creation, also finally returns after a year in hiding to "train" Mega Man by dueling him in various locations throughout his journey, but if Mega Man comes out the winner, he will open up the path forward to him. Proto Man disguises himself as "Break Man" prior to the Dr. Wily Stages (otherwise he is undisguised).
Upon defeating the main Robot Masters, four new levels open up, which are new versions of the levels they replace. Overall, these new levels are similar to the levels they replace, except much harder, for instance the new Spark Man level, features falling down a spike-lined shaft. In these levels, Mega Man is confronted by new robots called Doc Robots (one about half-way through the level, the other at the end), which take on the abilities of the Robot Masters of Mega Man 2.
After Mega Man is victorious over the eight Robot Masters and the Doc Robots, he confronts and battles "Break Man". After the duel, he teleports out and returns to the lab, where Dr. Light tells him that Wily has stolen Gamma and, of course, that Mega Man must pursue him immediately before he can wreak havoc with the massive war machine. Mega Man goes to Wily's new Skull Compound and, after defeating some new foes (including several clones of himself), he faces Gamma, who is under the control of Dr. Wily. Upon defeating him, the fortress begins to destabilize. Parts of the ceiling fall on Mega Man and Wily, but a red figure descends through the dust and rescues Mega Man. Wily has seemingly met his demise.
When he awakes, he finds himself in Dr. Light's lab. Dr. Light explains that he found Mega Man lying there when he came in. He then wonders aloud who brought Mega Man there, but before he has even finished his third word, a whistle splits the air, leaving no doubt in either Mega Man or Dr. Light's mind who was responsible for saving Mega Man. It appears that Proto Man is not evil after all.
Dr. Light takes Mega Man to a work table where he shows him a notebook that is filled with designs of Proto Man, confirming that Proto Man was the prototype master robot, and Mega Man's "brother", so to speak.