Thomas was built in 1912 and he arrived on Sodor in May of 1915. He was not supposed to be on Sodor, but a mix-up in Southern England led to him being sent to Sodor instead of his lazy brother 107, who was sent to the factory in Ireland where Thomas was supposed to work. Sir Topham Hatt chose to keep him because his brother refused to leave. He helped with the construction of the North Western Railway. After the railway was finished, he was used as a station shunter who shunted coaches for engines like Edward, Eagle, Henry and Gordon. He found the job very boring and often wanted to see the world. In 1923/1945, he did get two chances for this but each attempt went wrong. He left his coaches behind at the station while not realizing and was pushed much too fast by the Troublesome Trucks. However, in the same year, he was rewarded his own branch line after rescuing James after an accident. He was also given two coaches named Annie and Clarabel.
Thomas was the one who finally found out who the mysterious engine was, which turned out to be Neil.
SI3D's 2010 model of Thomas was used in the first half of season 1, Haunted Henry, and the majority of How the Diesel Stole Christmas ,then SI3D's 2012 "Christmas" model was used. Until the very end, where Wildnorwestern's RWS moder was used at the begging of Season 5. regular 2012 model made its debut in Stuck! and has been used ever since.
Thomas is based on a LB&SCR Billington E2 Class tank engine. The Class was built from June 1913 to October 1916. They were all withdrawn and cut up for scrap from February 1961 to April 1963.
- A Wretched Day for Henry and James (does not speak, spoke in original script)
- Gordon Goes Swimming (part 1 only)
- Bill and Ben the Brave Brothers of Brendam (mentioned)
- Stuck! (cameo)
- Engine Unknown
- A Tale of a Small Green Engine
- The Runaway Railcar (does not speak)
- Attack of the Railway Pirates (credits cameo)
- Steaming Sausage
- Diesels and Dragons
- Painful Memories
- The Creature
- A Turning Point for Edward (cameo, appears in flashback)
- End of the Line for Edward
- Ivo Hugh's Safari (cameo)
- Highly Sprung (cameo)
- Haunted Henry (part 1 only)
- How the Diesel Stole Christmas
- The Search for Smudger (cameo)
- Night Express to Vicarstown
- The Most Famous Engine (cameo)
Thomas will likely appear in Revenge of the Ghost Train.
- Tank Engine Mixup
- Two's Company
- The Trouble with Three
- Pride of the LNER
- Disgrace of the LNER
- Splendid Red
- Great Western Escape (cameo)
T1E2H3's RWS AppearancesEdit
- Coach Trouble (cameo)
- Right on Traction (cameo)
- Double Teething Troubles
- Derek and Gordon (appears in flashback, cameo)
- Thomas1Edward2Henry3: Episode II-Haunted Henry, More Branch Line Engines onwards
- JakerBraker123: NWR Origins, Specials
- RightonTracks10: How the Diesel Stole Christmas-A Tale of a Small Green Engine
Since Thomas is the main character of the show, he has obviously appeared in every season and special, he was later both CGI and models in Season 29. He is voiced by John Hasler in the UK and Joseph May in the US. He was previously voiced by Ben Small (UK) and Martin Sherman (US) in the 13-18th seasons, and Eddie Glen in Thomas and the Magic Railroad.
- When T1E2H3 voices him from Season 3 onwards, Thomas has a cockney London accent due to where his basis worked. It may also be reference to Johnny Morris' Narration.
- Despite being the title character of the real TV show, Thomas has had only two lead roles in the Engines of Sodor, in Engine Unknown (and even that is debatable as he didn't appear until the second half of Engine Unknown but was the one who found Neil) and Double Muddle. This is so that other engines can get a chance and the show doesn't just focus on him like the TV series.