I.M. Weasel is the extremely gifted and talented protagonist of the series. He is a handsome young weasel who, although famous, is not snobby or stuck-up and is rather generous (for in one episode he donated his kidney to a sickly little boy in a kidney transplant) and is the distinguished celebrity who everyone admires. He is highly intelligent and has many skills (both social and practical), and is proficient in most known professions. Though Weasel was never a bully to him, the fellow main character I.R. Baboon is always trying to top the admired Weasel because he wants an equal or better share in admiration, though unlike his rival, Baboon is extremely idiotic and the target for ridicule because of his bright red buttocks, but Weasel tries to generously help out his friend. Weasel is often assisted by a beautiful woman named Loulabelle who likes to dress as a nurse.
Notably since season 4, concept modifications were made for Weasel due to issues involving inter-specie intimacy being present in children's programs, as shown in previous seasons. In seasons 4 and 5, he rarely pursues with various attractive women, although in season 5, he did pursue Cow and Chicken's teacher (a least-attractive woman), but more in a love/hate manner. This, however, may be the cause after cutting Loulabelle out of the show and reflected issues involving the hybridchildren after being married to a Hispanic lady in one episode.