Peter Sam is a Narrow Gauge engine who is kind, well-mannered, and popular with the passengers and coaches. Even the trucks do not cause him trouble. Peter Sam is one of Sir Handel's friends, as they previously worked together on the Mid Sodor Railway, where Peter Sam acted less mature than he is now. Peter Sam's funnel was badly damaged in an accident with some troublesome slate trucks who mistook him for Sir Handel, and his funnel was later knocked off while going under a tunnel. It was replaced with a Giesl Ejector. He was initially teased for it, but soon he came to appreciate it.
- Peter Sam was previously named Stuart, but was renamed after one of the past owners of the Narrow Gauge Railway named Mr. Peter Sam.
- Peter Sam is based off of Edward Thomas of the Talyllyn Railway.