Thomas is a blue LB&SCR E2 tank engine, who originates from the London, Brighton, and South Coast Railway.
He came to Sodor in 1915, as a station pilot at Vicarstown until 1924-5, at which time he was transferred to Wellsworth following an incident with some trucks. Later that year, after rescuing James from his crash, he was given charge of the Ffarquhar branch line and two coaches named Annie and Clarabel. In the Railway Series, additionally he has a special express coach.
Thomas is a rather cheeky, but good hearted and kind engine and generally behaves well, except when he is getting into mishap from getting over-eager. He loves teasing the others, especially the bigger engines, such as Gordon and on occasion, brags about his superiority, but is always brought down to earth in due course by anyone who gives him the moral to learn, especially the Fat Controller, and his two coaches, Annie and Clarabel. If Thomas has one major character flaw, it is that he is forgetful and slightly impatient. However, he is also optimistic and idealistic.
Although their friendship has been turbulent at times, Percy is generally portrayed as Thomas' best friend, especially in the television series.
Thomas is youthful, playful and also loves making children smile and he'd do anything to make somebody's day a better one. Annie and Clarabel are his closest friends of all.
Thomas is based on the Billinton E2-Class 0-6-0T locomotives built for the London, Brighton and South Coast Railway between 1913 and 1916. He is apparently one of the last batch built as only these engines featured his distinctive extended side-tanks, projecting forward over the leading wheels and little down sweeps at each end of the footplate. The E2s were introduced in 1915 to replace earlier members of the E1 class, which had been scrapped. The last five in the ten strong class had extended side tanks to give a greater water capacity, but all engines had two inside cylinders and driving wheels 4'6" in diameter.
After many years of service, all of the Billinton E2s, both original and modified, spent their last working years at Southampton Docks, alongside the SR USA Tanks (Rosie's class), and they were all scrapped by 1963, the very last pair being numbers 31204 and 31209, the latter being amongst the last batch. Their replacements were BR Class 07 diesel shunters (Salty's class). There is, however, a campaign with the aim to build a new E2, and number it 110. Two E2s of the first batch were tested on passenger trips, as well as given the LB&SCR brown passenger livery, this was a failed experiment, the reason for it being that the first batch didn't carry enough coal and water. So the class was used only for shunting.
Thomas has a slight modification of having wheel splashers over his front wheels whereas the original E2s did not. Unlike Thomas, the E2s had footplates with dips at the ends or ones that were straight. Thomas only had a dip at one end of his footplate, which it was repaired after his accident with the Stationmasters house, making it straight.
Thomas is painted in the North Western Railway's standard blue livery with red-and-yellow lining and the number "1" painted on his tank sides in yellow with a red border. In the Railway Series, he carries two builder's plates on the sides of his cab.
When Thomas first arrived on Sodor in The Adventure Begins, he was painted teal-green with white-and-yellow lining. He had LBSC lettering painted on his tanks in yellow with a red border and had the number "70" painted in the same colours on the sides of his bunker. Upon his first visit to the Steamworks for a repaint, his metal frame devoid of paint is seen before being applied with a pink undercoat to keep water out from him, which would cause permanent rust damage.
In the first three seasons of the television series, Thomas had red lining on the back of his bunker. However, during the filming of All at Sea, the lining was removed for an unknown reason. Sam Wilkinson, the current railway consultant was responsible for bringing back the red lining on Thomas' coal bunker as of The Adventure Begins, and it will carry through into future seasons and specials.
- Season 100 - Geoffrey's Real, Toby and Philip, Henry the Warrior, Diesel Saves the Day, Trouble with Brakevans, Jealous James, The Railcar and the Passengers, Salty's Secret Story, Spencer the Show-Off, The Crashing Kipper (cameo), Trouble Trucks, The Lost Letters, Snowploughing at Christmas, The Christmas Engines (does not speak), Duncan's Dilemma, Henry in the Darkness, Timothy and the Aquarium, Sidney Helps Out, and Thomas the Hero
- John Bellis (Thomas and the Magic Railroad; original work-prints only)
- Edward Glen (Thomas and the Magic Railroad)
- Ringo Starr (UK; 2009 Children in Need charity single)
- Ben Small (UK; Hero of the Rails - eighteenth season)
- John Hasler (UK; The Adventure Begins onwards)
- Martin Sherman (US; Hero of the Rails - eighteenth season)
- Joseph May (US; The Adventure Begins onwards)
- Fabrice Trojani (France and French speaking Canada; sixth season onwards)
- Keiko Toda (Japan; first - eighth seasons)
- Kumiko Higa (Japan; Calling All Engines! onwards)
- Espen Sandvik (Norway; Hero of the Rails - Tale of the Brave)
- Martin Lange (Norway; eighteenth season onwards)
- Marco Vivio (Italy)
- Víctor Ugarte (Latin America; Thomas and the Magic Railroad)
- Javier Olguín (Latin America; Hero of the Rails - The Return of Sailor John)
- Héctor Ireta de Alba (Latin America; twentieth season onwards, excluding The Great Race singing voice only and The Return of Sailor John)
- Marcel Collé (Germany; Thomas and the Magic Railroad)
- Christian Stark (Germany; twelfth season onwards)
- Dirk Bach (Germany; Audio Books only)
- Janusz Zadura (Poland)
- Pepijn Koolen (The Netherlands; Thomas and the Magic Railroad)
- Jürgen Theuns (The Netherlands; Hero of the Rails onwards)
- Simcha Barbiro (Israel; Thomas and the Magic Railroad)
- Doriel Zohar (Israel)
- Caspar Phillipson (Denmark)
- Daniel Figueira (Brazil; Hero of the Rails onwards)
- César Díaz Capilla (Spain)
- Juha Varis (Finland; Hero of the Rails onwards)
- Richard Balint (Romania)
- Haris Grigoropoulos (Greece)
- Gia Trí (Vietnam)
- Prokhor Chekhovskoy (Russia)
- Pavel Tesař (Czech Republic; Hero of the Rails - seventeenth season)
- Jan Kalous (Czech Republic; Tale of the Brave onwards)
- In the Railway Series, Thomas was the first engine to have a number on the NWR. However, in The Adventure Begins, there were five other numbered engines before he was made number 1 to replace Glynn, a "Coffee Pot" engine from Sodor's branch lines.
- According to Brian Sibley, Wilbert used that number because it was the easiest to draw.
- Four Thomas models are currently on display: one at Drayton Manor in the UK, one in Japan at the Hara Railway Museum (previously on display at Nitrogen Studios), the large scale Thomas model used in the spin-off series, The Pack, in Japan at the Hara Model Railway Museum (previously on display at Thomas Land), and one for the touring Thomas and Friends: Explore the Rails exhibit, currently at the Minnesota Children's Museum.
- Thomas was coincidentally ranked #1 on WatchMojo.com's Top 10 Sentient Vehicles of All Time
- Thomas appeared in BBC's Children in Need charity single. He was voiced by Ringo Starr.
- Christopher Awdry lost the original Thomas model when he was in the US, although it was recently recreated for a sizzle promo for the 70th Anniversary.
- In Day of the Diesels, it was revealed that Thomas' driver is named Bob.
- Thomas was the first character introduced in the television series, unlike the Railway Series.
- As the series progressed, Thomas' eyebrows became larger and thicker.
- A promotional image of Thomas regularly appears in a photo frame on the children's program "Giggle and Hoot."
- A toy train resembling Thomas (with a grey face and a blue, red and yellow livery) appears in the "Bob the Builder" special, "Scrambler to the Rescue". Its coaches resemble the Express Coaches.
- In 2014, when artist Jenny Bell decided to paint a mural of the nativity at Nottingham railway station for Christmas, she added a golden model of Thomas into the picture. She used a wind-up model of Thomas from Hornby as a guide.
- A Hornby model of Thomas made a cameo in the 2003 Comic Relief.
- An ERTL model of Thomas made a cameo in GoodTimes Entertainment's home video "All About Fast Moving Trains".
- Thomas' LB&SCR number (No. 70) actually belonged to an LB&SCR A1 named Poplar, a member of Stepney's and Boxhill's class. The engine containing this number is currently preserved at the Kent & East Sussex Railway. The number 70 also represents the 70th anniversary of the Thomas & Friends franchise.
- Thomas' current voice actor for the American dub, Joseph May, was born in the same city where his basis spent their last service days (Southampton).
- Thomas' ERTL, Take-Along and Motor Road and Rail models have the red lining on the back on his bunker, even after it was removed in the TV series.
- Even after the red lining on the back of Thomas' bunker returned, none of the merchandising companies added the lining on the back of their Thomas models.
- Awdry's original model of Thomas depicts him as an LNER J50 0-6-0T with an extended coal bunker.
- In a Robot Chicken parody sketch of the TV Series, Thomas was voiced by Harry Potter actor Daniel Radcliffe.
- Thomas went through several changes in the television series:
- Season 1:
- He had a real looking brake pipe, which was tilted down so that it didn't touch the face.
- Season 2:
- He gained a smaller brake pipe on both front & back.
- Season 3:
- His footsteps got smaller.
- After Trust Thomas, the lining on the back of his bunker was removed.
- Season 6:
- His eyebrows became a bit bigger.
- His wheels became bigger.
- Jack and the Sodor Construction Company (large scale model only):
- His lamp becomes bigger.
- His brake pipe and buffers are bigger.
- There is a hole on the left side of his running board.
- His funnel is larger.
- The face masks used in the sixth season were modified.
- Season 7:
- His wheels go back to their original size.
- Season 8-10:
- His wheels keep changing the sizes during this seasons.
- Season 12:
- His chassis was opened, revealing the mechanisms inside the model.
- Hero of the Rails:
- His whistle became smaller, larger in length and is lower to the boiler.
- His cab is open.
- His number 1 became slightly smaller, and the red lining becomes thicker.
- He gained inside valve gear.
- The Adventure Begins:
- The lining on the back of his bunker returned permanently, this edition was re-added by Sam Wilkinson.
- His side rods become silver.
- His cab controls are consistently high detail (3D).
- Season 19:
- In Snow Place Like Home, the base of his whistle was gold, but switched back to blue in the next episode.
- Season 20:
- In all of the winter themed promotional photos, and episodes, the base of his whistle is changed to gold. But for the rest of the season, the base is blue, as normal.
- Season 100:
- The base of his whistle is blue in all of the winter themed promotional photos and episodes.
- Several of Thomas's screen used faces are owned by Twitter user ThomasTankMerch.
- Season 1: