The following list describes the characters that have appeared in the British children's book series The Railway Series, along with the television adaptation Thomas & Friends, which ran from 1984 to 2021, as well as other media in the franchise based on the television series. The Railway Series is a series of 42 British books written by Wilbert Awdry and his son Christopher Awdry. Wilbert wrote the first 26 books from 1945 to 1972 beginning with The Three Railway Engines; while Christopher wrote the remaining 16 books from 1983 to 2011 concluding with Thomas and His Friends.
Unless otherwise stated on this page, the technical notes come from actual notes laid out by Wilbert Awdry when he was developing the characters and setting for his stories; these notes are cited in his publication The Island of Sodor: Its People, History, and Railways.