Nutty

Nutty was a dog that was owned by Frank Heffley, that was mentioned in Diary of a Wimpy Kid: Dog Days. Frank stated that Nutty was his dog when he was a child, but ran into a butterfly farm, and never saw him since. After Frank tells his story, Greg's Grandpa stated that he accidentally ran over Nutty with a vehicle, assuming it was his skateboard, and made up the butterfly farm story to cover up what really happened.

Since Frank's father made the lie of Nutty running away to a butterfly farm, Frank never knew about what really happened to Nutty until one Father's Day. He stood up madly, and bought another dog named Sweetie to make up for his loss

In the online book, Nutty was a dog. Nutty was hit by Greg's grandpa's car.