Britt Allcroft (born Hilary Mary Allcroft, 14 December 1943 – 27 December 2024) was an English writer, producer, director and voice actress. She was the creator of the children's television series Thomas the Tank Engine & Friends (later re-titled Thomas & Friends), Shining Time Station (with Rick Siggelkow), Mr. Conductor's Thomas Tales and Magic Adventures of Mumfie. She also wrote, co-produced and directed the film Thomas and the Magic Railroad (2000).

She wrote and directed the movie "Thomas and the Magic Railroad", released in 2000, as well as providing the voice for the character Lady. The film was not a critical success, and Allcroft resigned in September 2000. Her resignation followed many years of internal stress within the company. In 2007, news surfaced on a Thomas fan site that the released version of the Thomas movie was a drastically edited version of Allcroft's original script and shot film - in effect, the claim was that production of the film had been taken out of her hands.