Junior Melchkin is a little robot who appears in BIT.TRIP RUNNER. He is seen in the background, just looking at CommanderVideo. Not much is known about Junior Melchkin, but it seems that he can be used as a wi-fi connector as shown in Runner2 when using an online internet connection to submit your scores. In BIT.TRIP FATE, his power-up features lasers that can pass through enemies. In GIGA, a single, large laser is fired.
Junior Melchkin appears in Runner3 in level 3-5, Girdle Springs Eternal. His Hero Quest is to find his three lizards with a password written on their backs so that he can access Machineland's wifi and watch his stories. Completing his request will unlock The Defector as a playable character.
It was revealed in a Runner3 Twitch AMA that Junior Melchkin was planned to be a playable character in Runner3. It is not known why he was replaced, but it may be because of his small stature.