Mettaton is a robot with a soul that was built by Alphys in the Undertale game. Mettaton was initially intended as an entertainment robot but turned out to be a human-killing robot. Mettaton later revealed that they acted as such only for Alphys to save the hero, to feel more important, and become closer to him. After having a switch on his back flipped to Neutral or True Pacifist Route, Mettaton transforms to Mettaton EX, which has a new body he especially asked Alphys to make for him. In this humanoid form, he has pale skin, a pink chest piece, and black hair. The chest piece has a speaker and some knob or a gauge. A fanart Undertale game progress bar for YouTube with Mettaton EX Dance.