Henry the Green Engine is a fictional anthropomorphic 4-6-0 steam locomotive from The Railway Series by the Reverend Wilbert Vere Awdry and his son, Christopher Awdry, and the spin-off children's television series, Thomas the Tank Engine and Friends.
He lives on the fictitious Island of Sodor with many other locomotives, including Thomas. He is engine number 3 on the North Western Railway, and was one of the first engines to be described, appearing in the first book. He is a little smaller than Gordon, who also appeared in the first book.
Although he is a hard worker, he can be prone to illness, which many engines put off as laziness.
He was originally a failed prototype engine, who as the result of a small firebox (which was a similar shape to Gordon's) was often ill and a poor steamer. The Fat Controller gave him special Welsh coal, which helped. But worse was to come – he had an accident while pulling the express fish train known as the Flying Kipper. The Fat Controller sent him to the works at Crewe, where they rebuilt him into his present shape. Henry was given a new firebox which gave him a similar specification to an LMS Class 5MT "Black Five" locomotive. This cured his illness completely.