Stephen, nicknamed "The Rocket", is an old and wise engine who works at Ulfstead Castle with Millie and Glynn, where he takes visitors around the castle grounds and across the rest of Sodor. Stephen is a jolly old engine with a positive attitude and a good sense of humour. He is a good-hearted and quick-witted engine and will not take any nonsense from engines like Spencer or Diesel. Some of the smaller engines look up to him for advice and he is always willing to get the job done.
- Stephen is based on Stephenson's Rocket.
- It is currently unknown when Stephen will appear.
- It is currently unknown who will be voicing Stephen.