Gamma is the final boss from Mega Man 3. It is a gigantic robot created by both Dr. Light and Dr. Wily (who at the time was pretending to have reformed) for peacekeeping. In order to power up Gamma, the doctors send eight Robot Masters to retrieve Energy Elements from mining areas, however they suddenly turn berserk and it is up to Mega man to defeat them and retrieve the elements. After Mega Man returns all elements, Wily steals Gamma and runs away with it, intending to use it for world domination.
The fight with Gamma takes two phases. In the first a small robot head is attached to the cockpit, which continuously shots down. The robot head can be easily defeated with the Shadow Blade. After it is destroyed, Wily attaches the actual Gamma head and controls it directly, shooting from it's mouth and punching. It's weakness is the Top Spin, which can defeat it in two hits.
After Gamma is destroyed, Wily's castle starts falling apart and both him and Mega Man get caught under debris. Proto Man saves Mega man but is unable to find Wily, who gos missing. It is later revealed he somehow escaped the crumbling castle.