Thomas & Friends: King of the Railway is a 2013 British computer-animated fantasy comedy adventure film that functions as the seventh feature-length special based on the British television series Thomas & Friends. The film was produced and distributed by HIT Entertainment with animation production by Canadian-based Arc Productions, who took over animation from Nitrogen Studios for the series and following specials from then on. It marks the debut of Mark Moraghan as the narrator for both English versions of the series. The movie centres on Thomas in the search for his new friend Stephen, who goes missing during the restoration of Ulfstead Castle.

The film had a two-day Limited theatrical release in the UK on 23 August 2013 and was released to DVD shortly afterward.