Stephen Topham Hatt (born 1941) is Sir Topham and Lady Hatt's grandson, Bridget's older brother Dowager Hatt's great-grandson and Sir Lowham Hatt's great-nephew. In The Railway Series, he took over his father's role as controller of the North Western Railway in 1984 and became Sir Topham Hatt III in 1997.
Bio in the Railway Series
The Hatts spent a long holiday on Toby's old line in East Anglia. Stephen was excited when he first met Toby, but Bridget accidentally offended him by assuming he was an electric tram.
He became the Fat Controller in 1984, succeeding to his father's baronetcy in 1997. In 1970, he married Helen Margaret, a distant cousin and granddaughter of the Reverend Nicholas Dreswick, the much-respected historian of Sodor. They had three children: Richard Topham, born in 1972 and no doubt destined to be Sir Topham Hatt IV (his father will be seventy-four in 2015, though he has, as yet, given no hint of retiring), Charles Nicholas (1974-) and Emily Helen (1977-).
With great skill, he masterminded the arrangements for the royal visit in 1995, when he welcomed the Prince of Wales on his visit to Sodor.
Bio in the Television Series
Stephen had never grown up to be controller, and has always remained as about the same age. He was amongst the boys who teased Daisy about bull's-eyes, and was also amongst the boys who teased Sir Handel about George. He and Bridget helped Toby discover an old castle. He thought that Edward was the strongest and the best, after Edward pushed Duck, Gordon, and their trains into Knapford Station. He and Bridget flew a kite, which got blown away, but Thomas, along with Charlie, Percy, Edward and Emily retrieved it. He and Bridget later caught chickenpox, convincing Henry that engines could catch chickenpox as well.
- Matt Wilkinson (UK; thirteenth season only)
- Teresa Gallagher (UK; fourteenth season onwards - US; nineteenth season onwards)
- William Hope (US; thirteenth season and fourteenth season)
- Tomoko Naka (Japan; first season only)
- Hiromi Nishida (Japan; Toby's Discovery only)
- Chisato Nakajima (Japan; fifth - sixth seasons)
- Kumiko Izumi (Japan; seventh season only)
- Yasuhiko Kawazu (Japan; eighth season only)
- Yuko Mizobe (Japan; tenth season only)
- Yūko Nishi (Japan; thirteenth season only)
- Takayuki Kawasugi (Japan; fourteenth season only)
- Keiko Nemoto (Japan; nineteenth season onwards)
- Blanche Ravalec (France and French speaking Canada; sixth season onwards)
- Lena Meieran (Norway; thirteenth - fourteenth seasons)
- Aaron Lee Ullmer (Germany; Audio Books only)
- Artur Pontek (Poland; thirteenth season onwards)
- Petri Hanttu (Finland; thirteenth season onwards)
- In the magazines, he and Bridget have a friend named Marcus.
- In the magazine story, The Hallowe'en Special, it is said that Stephen and Bridget live on the Mainland and only come to stay with Sir Topham and Lady Hatt every so often.
- In Saved from Scrap, Stephen's model was used as one of The Vicar's sons.
- From the third to seventeenth seasons, Stephen wore a green sweatshirt instead of a jacket and tie.