Thomas & Friends is a British children's television series that aired for 24 series and 584 episodes from 9 October 1984 to 20 January 2021. Based on The Railway Series books by the Reverend Wilbert Awdry and his son Christopher, the series was developed for television by Britt Allcroft. The series follows the adventures of Thomas, an anthropomorphised blue steam locomotive on the fictional North Western Railway on the Island of Sodor with his friends Edward, Henry, Gordon, James, Percy, Toby and others who are engines of The Fat Controller.

In the United States, it was first broadcast along with the spin-off series, Shining Time Station, on PBS' PTV Park block on 29 January 1989. The rights to the series are currently owned by HIT Entertainment (a subsidiary of Mattel), which acquired Gullane Entertainment in July 2002. HIT was folded into Mattel in 2016.

A new 2D-animated series, Thomas & Friends: All Engines Go, premiered on 13 September 2021 on Cartoon Network's preschool block Cartoonito.