|Non-Canon: Characters and events depicted in this article are non-canon.|
Arnold is a male student who goes to Madison Elementary School.
He wears red glasses and has brown eyes. He is chubby and short and has orange, short hair.
- Goodbye and Good Riddance (first appearance)
Arnold shares his first name with Arnold Perlstein from The Magic School Bus series, who also has glasses and orange hair.
- He has a blog about the alien sightings, much like Jimmy Jones.