Sherman is the class pet in Ms. Godfrey's room. He is a gerbil. He was brought to class by Ms. Godfrey on November 10th, 2014, and the class voted his name to be Sherman, being named after William Tecumseh Sherman. He plays a big role in Big Nate: Hug It Out! Although Hug it Out was a collection, not a real story, he was in many strips back then.
He expresses his feelings, or "talks" through thought bubbles, referencing characters Garfield and Snoopy. He is also the only animal in the series to communicate, but no one understands him because he doesn't actually speak. Nate understands him the way Jon understands Garfield.
Once, Gina Hemphill-Toms brought in a troll doll so Sherman would have a buddy. Sherman found it very humiliating, and Nate later removed it, as he was on gerbil duty. Later, she brought a rubber duck.