The planet of Junk was originally a refuse point in the middle of space for discarded materials from the Cybertronian society. Over the eons, the refuse point became a large ball in space. Eventually an esoteric group of transformers known as Junkions inhabited it and a unique culture formed on the planet, which is close enough to receive television brodcasts from Earth with only a decade or two of lag.

Junk was first seen in Transformers: The Movie.