Metal Gumball is one of Gumball's evil alter-ego's,he's a perfect replica of Gumball,but metal and he was created by Anais,His debut is The Heroes.at the middle-end of the episode,he turned into the Evil King Metal Overlord.
Metal Gumball looks like Gumball but he's metal and too powerful,his eyes are black with holographic red pupils that blink when he talks,he has bolts on his whiskers which are scratch marks and his nose is gray.His wrist and shoulders are yellow and his entire body is gray,also his arms are too thin and he also have a core in his chest which fires various types of laser beams.
Metal Gumball is evil and have a naughty nature,he has no friends except for Evil Gumball and Mr.D.his arch enemies are Gumball,Super Gumball and Zack.He thinks he's Gumball and Gumball is a copy.He's a reference to Metal Sonic.
Neo Metal Gumball
Neo Metal Gumball is a different version of Metal Gumball,He always appears when Gumball is prepared to fight him,There are many arrows on his face and he wears Gumball's Date clothes.He transforms into Metal Madness when defeated.
Metal Overlord is the final form of Metal Gumball,Neo Metal Gumball can transform into him when defeated,he's giant and he can fly,he can only fight in space and he's a bit invinsible.if Super Gumball fights him for a while there will be a core,if it gets hit,Metal Overlord will be destroyed and turn back into Metal Gumball and automatically turns off.