Proto Man

Proto Man is a Robot Master wearing shades with a shield and yellow scarf created by Dr. Light and considered to be the brother of Mega Man and Roll. He first appeared as a mini-boss in Mega Man 3.

Mega Man 3
Proto Man first appeared as a mini-boss in Mega Man 3. It's past in the Gameboy version of some stages. After Mega Man beats Doc 8 times, he'll fight Mega Man, disguised as Break Man. After Wily's defeated, he brings back Mega Man to Dr. Light's lab.

Mega Man 4
After Mega Man defeats Cossack, Proto Man rescues her to he and her father. After her daughter's rescued, Cossack builds Beat.

Mega Man 5
He's framed for kidnapping Light and doing a robot attack. Mega Man later finds out that Wily created Dark Man to impersonate him. He appears to reveal the description and later helps him by lifting the roof of Wily's Castle when he saved Dr. Light.

Mega Man 6
Proto Man only appeared in Tomahawk Man's stage to give him the Energy Balancer upgrade. With it when he collects the Weapon Energy when the Mega Buster is equipped, it restores the weapon with the last energy in it.

Mega Man 7
Proto Man only appeared in Cloud Man and Turbo Man's stage. He gives Mega Man hints to certain secrets.

Later, he appears in Shade Man's stage, behind the Sniper Joe 01 after defeating the mini-boss VAN Pookin. Mega Man fights him and if he took enough damage, he'll give him his Proto Shield.

Mega Man & Bass
Proto Man appears in the opening, where he's trying to shoot King, but he's sliced in half, Mega Man shows concern and to go to Light for repairs, while Bass ignores him and claims he's the most powerful robot.

Mega Man 9
Players can only play as Proto Man by downloading him for 200 Wii Points.

Instead of Rush, he can defend attacks with his Proto Shield.

He can slide and charge his arm cannon and fire only a pair of shots.

In the ending, he can see Galaxy Man as a UFO.

Mega Man 10
As Proto Man, there are a few items in the shop and the prices are increased, for example, an E Tank costs 40 screws.

In the middle of Wily's Castle, he's infected with virus and collapses, like Roll as she's infected by Roboenza.

Other media
Proto Man appears in every episode in Ruby Spears' Mega Man as Wily's minion, along with Guts Man and Cut Man.