The Gromble, is the initial main antagonist, later anti-hero of Aaahh!!! Real Monsters. He is the intimidating and strict headmaster of the monster academy, who demonstrates his tough love by belittling his students for poor scares. The Gromble has been seen eating one of his students in one bite (although he spits him out after chewing him up). Gromble calls his shoes "snuggle bears" and loves relaxing in his bed. He is sometimes referred to as "The Gromble", "Gromble Sir" or "Mr. Gromble". Gromble is teacher of almost every monster child shown in the series. He is strict and wants his students to reach their full potential. He seems to favor Oblina, likely because she is the best student.