Jeffrey Swanson is a character that appeared in Diary of a Wimpy Kid: Old School. He is one of Greg Heffley's cabinmates that stayed at Hardscrabble Farms for a week. Jeffrey Swanson is one of the boys who jumped during the trust-fall activity. His groups' chaperone, Robert Jefferson, showed everyone how to make a net with their arms to catch whoever jumps. When Jeffrey jumps and falls, his weight made him bangs into Rowley Jefferson and Gareth Grimes, which made them collapse and smash into each other. One of Gareth's teeth is missing until a cabin-mate named Emilio Mendoza found it stuck in Rowley's forehead.
On page 194 of Old School, he gives a "piggy-back" ride to Emilio Mendoza (since Emilio cannot see correctly without his glasses, which had been smashed in the high-five of Jeffrey and Greg), and carefully steps into Mr. Nuzzi's footprints during there raid when Mr. Nuzzi covers the area around there cabin with baby powder and leaves his own footprints. Everyone in Jeffrey's group walks in the footprints of Mr. Nuzzi so no one could tell they had left, by using Mr. Jefferson's boots that closely matched Mr. Nuzzi's footprints.
- Diary of a Wimpy Kid: Old School (First and only appearance)