Howell the Hutt is the nickname the students gave Mr. Howell.
It started in a chapter from the first case file where Kellen compared Mr. Howell with Jabba the Hutt. It became a running gag throughout the book series. Mr. Howell secretly known that the kids were calling him "Howell the Hutt", as revealed in The Surprise Attack of Jabba the Puppett. He is the weilder of Jabba the Puppett. It turns out that Jabba is Howell's favorite character.