This article is about the diesel engine. You may be looking for the Story Library book or the Engine Adventures book.

"Devious" Diesel, as his name implies, is a sinister diesel shunter who originates from the Other Railway, and is the first diesel engine (at least standard gauge-wise) to arrive on Sodor. In the television series, Diesel becomes a permanent resident of Sodor.


The Railway Series

When Diesel came on trial to the North Western Railway, Duck was asked to show him around. Duck was unimpressed by Diesel's claims of being "revolutionary" and left him to his own devices. As a result, Diesel was made into a laughing stock by the trucks for trying to pull some rusty old trucks and failing spectacularly. Diesel then blamed Duck for not helping him and swore a vendetta plan; he spread rumours that Duck had given the big engines rude nicknames, which led to Duck being sent to Wellsworth pending an inquiry into the matter. Diesel meanwhile got too big for his buffers and started telling lies about Henry, but he was found out and sent home in disgrace.

Several years later, Diesel was brought back to help on Thomas' Branch Line whilst Percy was being repaired. Diesel tried to win Thomas and Toby over, without success and after he destroyed an old truck, he was to be sent away. However, on his day of departure, Clarabel slipped on oily rails left by Daisy and came off at some points near Dryaw. Diesel - realising that Thomas was blocking his only way home - went to the rescue. Clarabel put in a good word for him and Diesel - although he returned to the Other Railway - has since always been welcome on Sodor.

Thomas & Friends

Diesel's first visit to Sodor is directly adapted from the Railway Series and happens virtually the same way. Following occasions where Diesel is seen in the background are when he attended the Christmas Party at Tidmouth, attended the celebration of City of Truro's visit, and shunted trucks in Knapford Yards.

Years after their first encounter, he returned when Duck and Percy needed help at Brendam Docks. Since Diesel was the only engine available, Sir Topham Hatt was forced to give him a second chance, much to Duck's hurt. Duck and Percy refused to work with Diesel and stayed in the shed, leaving Diesel to work by himself and causing the work to pile up, which made Sir Topham Hatt to intervene and send them back to work. Things did not improve, and Diesel bumped into Percy after his driver failed to put the brakes on properly. He then roughly shoved some trucks, spilling the loads everywhere; Duck and Percy remained quiet out of fear of being telltales. This convinced Diesel that he could be as bad as ever and shunted some trucks of china clay right into the sea. After this, Sir Topham Hatt sent Diesel away, intending his expulsion to be permanent, but Diesel somehow mysteriously returned to give Mavis advice, tease Edward and Trevor for being old (in a deleted scene), and taunt Gordon about the triumph of diesel power on the Mainland. It is possible that these events happened during Diesel's stay or that Diesel returned at some point with goods from the Mainland.

When Henry was derailed by some trucks, Diesel was brought back as a last resort to do his goods work. Unfortunately, his attempt to have Sir Topham Hatt replace steam engines with diesels backfired when he tried to prove that he was the world's strongest engine which resulted in him falling into a barge and he was sent back to the Mainland yet again.

Later on, Diesel returned yet again, this time to assist Fergus at the Sodor Cement Works. Diesel became jealous of Fergus' reputation as the "pride of the Cement Works". He also became cross because of Fergus' deep regard for the rules and always telling him "Do it right", especially while carelessly bumping some trucks out of the hopper. He then concocted a scheme to make Fergus run away. Diesel was partially successful (he managed to make Fergus abandon his post for a time), but was ultimately foiled. Amazingly, Diesel was not sent back this time around, as Sir Topham Hatt told Thomas and Fergus he would move Diesel to the smelters (possibly because he might have not seen any point in bringing Diesel in as a spare engine and then sending him back for his bad behaviour); Diesel has remained on the North Western Railway since.

Despite remaining tricky and devious, Diesel learned how useful steam engines can be when Thomas brought fresh diesel fuel for him and the other diesel engines and James pushed him back to the Repair Yard when he broke down. However, he tried to convince Gordon that he was old and clapped out, Ben that there was a monster inside a tunnel and Thomas about the "Curse of the Cliffs" and scared him at Halloween.

But Diesel proved to have a good side inside him when he told Emily about his record he made for shunting lots of trucks in one day than any other diesels and proved to Thomas that he did not ruin the photograph for the billboard on purpose.

Although Diesel made fun of James when he was painted pink, he tried his best to prove himself to be as useful as the steam engines when he took all of the Jobi wood to the Sodor Search and Rescue Centre - only to put himself in danger requiring Thomas to rescue him. However, Diesel tried again to prove how special he is when he took Thomas and Rosie's loads to market and stole James' pigs so that the children could see them. But it was only when Diesel brought the load of slate for the school that he proved himself Really Useful.

Diesel was also one of the diesels that took over the Sodor Steamworks. He later teased Flynn for just standing around and doing nothing.

In Blue Mountain Mystery, Paxton told Diesel about Luke and Diesel tried to get Luke sent away from Sodor, but he failed when he was scolded by the Fat Controller.

When he and Percy collected a calliope, he thought Percy would not be able to make it play but was surprised when he did.

In the seventeenth series, Diesel was one of the diesels that brought the Christmas decorations to Tidmouth Sheds. Later, he was biffing trucks around even when Edward told him to stop. Diesel spilled the milk in the trucks and when the Fat Controller opened the truck doors, the milk splashed all over his trousers. When Hiro told Diesel, he told Hiro to toughen up with the trucks. But when Hiro would not listen, Diesel coupled himself up on the back of Hiro's train and helped the trucks play tricks on Hiro. To make the trucks stop, Hiro braked suddenly before the platform, causing three barrels of cream to splash all over Hiro, Edward and the Fat Controller. Diesel tried to get away but was blocked off by Thomas. As punishment, Diesel had to learn the proper way of handling trucks by Hiro.

In the eighteenth series, Diesel, along with NormanSidney, Den and Dart, hid from Paxton at the Dieselworks, which resulted in Paxton going on a wild goose chase to find all of the diesels and ended with Diesel running out of fuel, so Paxton helped him to the next station to get some more. Later, he argued with Thomas over who should be the back engine for a train of trucks heading from Ffarquhar Quarry to Brendam Docks. He later tried to delay Mavis returning to the quarry, which led to Thomas taking the train by himself, which resulted in him having an accident. Diesel even tried to blame Mavis for it, but the Fat Controller was wise to his tricks and he let Thomas work with her instead. He later joined the engines at Knapford during the Christmas Holidays and agreed with the Fat Controller that the last train would possibly be cancelled. He also teased Samson about how the tank engine got lost when he first came to Sodor.

In the nineteenth series, he covered Paxton in a cloud of black smoke from his engine, leaving Paxton's face covered in black spots.

At Christmas time, Diesel was being very unhelpful with the extra work, so Thomas, Emily, Salty and Paxton made a plan. On the night before Christmas morning, they pretended to be ghosts to scare Diesel, scaring him to the point where he flew off the tracks and derailed. After he was recovered the next day, he learned the true meaning of Christmas. On Christmas morning, Diesel was feeling very merry and he brought the Fat Controller to the Earl's Christmas lunch at Ulfstead Castle.

He later tricked Percy into going to an old quarry so that he could do Percy's job of picking up the Mayor to take him to a ceremony. Diesel later found Percy stuck in a flood with his fire out. He tried to rescue the tank engine but only made the situation worse when the water damaged his generator, so he got stuck too. After the two were rescued by the Search and Rescue team, Diesel was sent to have his engine repaired.

In the twentieth series, Diesel was shown to care for some ducklings that he thought were cute. Later, Annie and Clarabel played a trick on Daisy while Thomas was on quarry duty and after Diesel was sent to pull them instead, much to their dismay though Diesel was polite to them despite bumping them.

In The Great Race, Diesel wanted to go to the Great Railway Show, but the Fat Controller was hesitant. To prove himself, Diesel had crates put over Den, Dart and Paxton so that they would resemble trucks and put them in a long train. When the Fat Controller was in the final stages of choosing who would go to the show, Diesel planned to demonstrate how strong he was by pulling the train, while in reality, Den, Dart and Paxton were doing most of the work. However, his unusual train was blocking any way into Knapford Yard. Thomas was coupled to the train both so that he could get into the station and so that he could prove himself worthy to go to the show. The diesels heard Thomas' whistle and thought it was Diesel's horn, so they began pushing, much to Diesel's horror. Thomas then collided with Norman at a set of points and lost his left buffer as a result. Diesel later got stuck inside one of the crates and was accidentally loaded onto a ship by Cranky. He somehow managed to return to Sodor before the events of the twenty-first series.

In the twenty-first series, he damaged Daisy's springs and caused mischief between her and Harvey by telling them both that the other was boasting about being unique, which led him into the sea after his plan failed. He later brought the coal delivery to the steam engines during a big freeze.

In the twenty-second series, he, Bill and Ben laughed at Thomas and Rosie because of their friendship at Brendam Docks after the devious diesel bumped into the red engine while Cranky was unloading a crate of roses during Valentine's Day.

In the twenty-third series, he continued to cause more confusion and delay than before by sending Rebecca to do the other diesels' jobs improperly as a trick to pay them back as they do not get into trouble as he does. Unfortunately, he was cornered at the Dieselworks and Rebecca's honest nature meant that she was quick to tell Sir Topham Hatt about her favour for Diesel. He was very cross with him after hearing what had happened that day, with Diesel left to be upset about being in trouble again. He also wanted some engines who think he is not reliable at all - particularly Paxton and Nia - to come and find him hidden with some glow-in-the-dark paint at the Blue Mountain Quarry, to which they told him off for not doing his jobs for two whole days due to his self-interested and pushy attitude.

In the twenty-fourth series, when Sonny was having his second chance upon arriving on Sodor and being not trusted because of his previous status quo of a thief, he takes advantage of this and uses him to be his "friend" and do his jobs for him due to the latter wanting to be really useful and stay there, but eventually, following an argument with Percy at Ffarquhar, the tank engine found out his plans and got upset with him, leading him to derail at a dig site. Luckily, Sonny changes his mind and rescues him, albeit accidentally derailing his trucks to which Sir Topham Hatt was going to send him away. Feeling guilty, Diesel admitted that all the chaos was his fault and the tank engine was officially accepted on the railway.


Diesel is, in essence, the average pantomime villain. He is oily, malicious, devious, scheming and full of ideas to get revenge. He views himself and any other diesel as highly above the steam engines and believes that all diesels are "revolutionary" - he has also claimed diesels should be "rough and tough", as an excuse for bullying the other engines. His antics give diesels on Sodor a bad reputation, which causes most steam engines (particularly Duck and Thomas) to mistrust him. His rough demeanour also affects his fellow diesels, who are often victims of his tricks alongside steam engines, mainly diesels who are friendlier to steam engines and are just nice in general, with Paxton being a prime example.

However, despite his antics, Diesel still wants to prove himself to be a Really Useful Engine. He is also very proud to be the first diesel on Sodor and seems to have a soft spot for cute ducklings.

Lately, Diesel is portrayed as a typical bully with a lack of forethought. While sinisteringly cunning, he usually neglects to think of what would happen if things were found out and due to the transparency of some of his plans, he always gets his comeuppance in the end. His distaste for Steam Engines has also been dropped, being replaced by a mean-spirited prankster nature and inflated arrogance. He also shows several hints of manipulative and self-serving tones, which happened for example almost ruining Sonny's new life on Sodor when the former was having his second chance upon arriving.

Technical Details


Diesel is based on a BR Class 08. Over seventy members of this class survive today in preservation, while around 100 remain in service on the national rail network. They are in fact the most successful shunting engines in the world, with 996 of them built. Splatter, Dodge'Arry, BertPaxton, Sidney, Ulli and the Mainland Diesels are also members of the class, along with several others.


Diesel is painted in BR black, which was the standard livery for shunting engines from 1948 until the mid-1960s. His side rods were painted silver until the sixth series, where they were repainted black.


Thomas & Friends


He was also likely to appear in the WWII film.

Music Videos

Learning Segments


Magazine Stories

Diesel also appeared in the magazine stories, A Special Story about Steam, Blowing About!, Bulgy's Dream, Clean Getaway!, Diesel Display, Diesel's Drums, Diesel's Nasty Turn, Diesel Causes Delay, Engine Plates, Fishy Diesel!, Glider Rider, Henry and Diesel, Making a Mess!, Mountains and Mess!, Nice Neville, Percy and the Trucks, Rhyming Engines, Ride and Slide, Road Ride, Rocking About, Slick Trick!, Sodor's Strongest Engine, Special Places, Stick with Steam, The Christmas Sacks, The Runaway Percy and The UFO

Annual Stories



Audio Files


First used Last used Sound Effect
Series 2 Active
Diesel's Horn
First used Last used Sound Effect
Misty Island Rescue Series 14
Generic American Horn


  • Diesel was the first diesel to be introduced in both the Railway Series and the television series.
    • He was created when Eric Marriott, the editor of the Railway Series at the time, suggested that Awdry should introduce a diesel in order to keep the books up to date.
  • In some merchandise lines he is referred to as "Devious Diesel". It was not until the seventh series episode, Fergus Breaks the Rules that he was referred to by this name on-screen.
  • In Series 2 and Series 3 Diesel's coupling rods were white & silver, but from Series 6 onwards his coupling rods are black.
  • Between the thirteenth and sixteenth series, Diesel was the only character from the model series to still be voiced by the narrator in the CGI Series. However, this was only in the US narration.
  • As revealed in the tenth series episode, Emily and the Special Coaches, Diesel is a record holder for most trucks shunted in a single day.
  • Diesel has travelled at well over his top speed of 20 miles per hour on numerous occasions in the television series.
  • Throughout voicing Diesel, In the US dub Martin Sherman gave him a New Jersey accent. Michael Brandon gave him a gruff American accent, while in UK dub 13th series onwards & the US dub 19th series onwards Kerry Shale gives Diesel a faint hoarse Cockney accent.
  • Diesel's face in the magazine stories is often smaller than in the television series.
  • According to the magazines and the DVD Bingo game, it reveals that he and Bulgy are good friends.
  • Nathan Clarke did an audio sample for Diesel on his DAA Management Page.
  • Diesel's television series model is now owned by the Explore the Rails exhibition, previously on display at the British Museum during the 70th anniversary.
  • During production of the HiT Entertainment model era, Diesel had a sleepy face mask made and was not used on-screen.[3]
  • Although Diesel does not have any in-canon number, he has been portrayed several times to have the number 1 in the Thomas Creator Collective, most notably in The Return of Diesel when he becomes the leader of a group of diesel shunters on the Mainland.
  • He is the only character to not appear in the Fifth series.



* RWS only | ** T&F only

* RWS only | ** T&F only | --- Dropped

*Disclosure: Some of the links above are affiliate links, meaning, at no additional cost to you, Fandom will earn a commission if you click through and make a purchase. Community content is available under CC-BY-SA unless otherwise noted.

Fandom may earn an affiliate commission on sales made from links on this page.

Stream the best stories.

Fandom may earn an affiliate commission on sales made from links on this page.

Get Disney+