Dr. Dextrose first appeared in the episode "The Real You," where he gives his speech at Princess Bubblegum's Science Barbeque. He also seems to have a dark side, when he made an evil face at the end of his speech.
He looks like a marshmallow. He wears a black suit, with a scientific parasite inside its pocket. He has a rouge hair that is a dark-ish red. He also wears a small microphone.
- His name comes from an ingredient in marshmallow, dextrose.