Mr. Toggle is first introduced as the janitor of The Shreek School. He is described by Dr. Shreek as a mechanical genius. When Jerry Hawkins first encounters him, Mr. Toggle offers to show him his workshop. Jerry accepts, and is shown the various incredible inventions he's been developing. When Jerry sees him next, Mr,. Toggle rescues him from Dr. Shreek, shutting him down, and revealing him to be another one of his robotic creations.
Mr. Toggle quickly turns on Jerry, and tells him he needs his hands. Toggle reveals he wants to make beautiful music without human error, but hands are too complex to build, so he takes them from living specimens. Before he can get Jerry, Toggle is dragged away by the ghosts of the former Shreek School students.
Toggle is described as a tall, wiry man with black hair and a black beard.
Toggle is obsessed with his inventions, and finding new ways to make music. It can be assumed he has an odd sense of humor since he deliberately names his creation Dr. Shreek. Like Shreek, he is kind at first, but quickly turns deranged and aggressive. It is likely Shreek's personality is based much off his own. He shows little concern for the lives of the students, prioritizing their music over all things. Toggle is shown to have extraordinary intelligence through his various creations.
- In the televised adaptation of the book, Mr. Toggle's character is changed. Where the book has him need hands for his inventions, the episode establishes his need for hands is because he never knew how to play the piano, hence he also has a history with the ghost haunting Jerry. It is revealed the spirit is of his former piano teacher. At the end of the episode, Toggle is forced to play piano forever as punishment for torturing Jerry.
- Mr. Toggle's first name is never revealed in the book, but he is referred to as Andrew Toggle in the episode based on the book.
- Toggle is one of few Goosebumps antagonists to have actually killed people.