Moby

Moby The Robot is an orange-sepia toned robot which was once black but turned orange from a tan.

BrainPOP
Tim is a teenager who does most of the talking in the movies and understands what Moby says. The design on his shirt usually matches the topic being covered. At the beginning of each video, Tim reads a letter from a student asking about the topic. Often at the end of the movies, Moby will humorously annoy Tim. Moby is Tim's friend but loves to drive him crazy. Moby helps out by fetching things for Tim and asking questions about the topic they are discussing. As a robot, he can do things that people are unable to do, such as changing his hand into a freeze-ray, sending himself back in time, throwing garbage into a black hole in space, removing his head, and using lasers. Some of the movies, such as the Earth, Radar and Milky Way videos, imply that Moby is of an extraterrestrial origin. However, the Leonardo da Vinci movie implies that he was invented by da Vinci

BrainPOP jr
Annie is a young girl who narrates the movies. She wears red framed glasses and also works with Moby. She has a teenage sister named Mia. There are many hints in BrainPop Jr. that Annie is Mexican. For instance, her dog's name is Señor Maurice, and she sometimes refers to her father as "Papi".

In BrainPop Jr., Moby shows his emotions more often, like crying or getting excited. Moby is more kind-hearted in BrainPop Jr. than in BrainPop. He can also do things that he can't do in the BrainPOP videos, like sneeze, sweat, and drink water. He can also be sick and smell flowers.