Dark Star Guppy is the main villain of the series.
Dark Star Guppy is a malevolent, yet dim-witted villain who's rarely nice to anyone. His favorite thing to do is scare people. He enjoys hanging out with Dark Booster and Rawfley, but hates cold weather and the Bubble Guppies. His voice actor is Zachary Gordon.
Dark Star Guppy is a skinny charcoal black guppy with red eyes and a gray tail. The top of his hair is violet and shaped like a star. He shares his wicked smile with Rawfley, so it is speculated that they are related in some way.