Baby and Buu

Baby and Buu are two semi-organic aliens that terrorize the back alleys of a populated city at night. They are actually brutal murderers who graphically dismember, eat, and actually refrigerate the leftovers of kills from the night before, despite being baby blue and bubblegum pink respectively. The Saiyans fight them one time before, but since the Wish to grant planetwide immortality, they reason that the two serve as a system of 'checks and balances' against the ever-increasing population, and some of the victims were actually involved in illicit activities to begin with.

Information
Comedic Relief

Threat: Minimal, but still credible

Trivia

 * Buu was originally grey when the series started, but after having gotten tangled up in a taffy puller (erroneously referred to as a cotton candy machine) while terrorizing a fairground, he gained a pink texture to which he has since kept. It helps him attract children and have people take him less seriously.
 * Buu seems to have a taste for children and 18-23 year old women due to their inherent lack of musculature and higher proportion of body fat, whereas Baby likes to eat odd or particularly unusual individuals, most often consisting of older men. Neither are very picky.
 * Baby and Buu are nearly able to kill Goku, Goten, and Alex, but actually succeed when they encounter Darrius for the first time. Other than that, they attack humans as they are easier to deal with and scream when frightened.