Diesel

"Devious" Diesel, as his name implies, is a sinister diesel shunter who originates from British Railways, and is the first diesel engine to arrive on Sodor. In Thomas & Friends, Diesel eventually becomes a permanent resident of Sodor.

Personality
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 distrust 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 and Sidney being prime examples. As such, Diesel has very few friends, mostly associating with diesels whose personalities align with his, such as Diesel 10 or ‘Arry and Bert. He also enjoys using gullible engines, such as Paxton and Rebecca, as pawns in his plans.

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, which he is embarrassed by because he believes it ruins his tough exterior. Diesel will also more often than not focus more on his own work than help anyone else, but he will help any engines, steam or diesel, when it comes down to it. Due to the amount of chaos his web of lies set off on his first day on Sodor, Diesel has often been seen as a liar by the other engines, leaving them to blow off his news as bluffs until absolutely proven. This is not helped by the fact that he lies whenever he gets the chance, further reinforcing their beliefs.

Lately, Diesel is portrayed as a typical bully with a lack of forethought. While sinisterly 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 (most likely due to the show targeting a younger audience), being replaced by a mean-spirited prankster nature and inflated arrogance. He also shows several hints of manipulative and self-serving tones, as he can be found as very lazy. Proving this, he managed to trick Sonny into doing his jobs for him, though much like Daisy and Dennis, both of whom who have tried similar tactics, Diesel was immediately struck by karma, having his luck deteriorate due to his selfishness. He also made fun of James when he was painted pink and Thomas when he was dressed up as a monkey, finding both to be humorous contrary to how they actually felt. Diesel does know when he goes too far, however, and usually owns up for his misdeeds if the situation demands it. This has allowed him to form genuine lasting friendships with such engines as Daisy and Harvey.

Basis
Diesel is based on a British Rail (BR) Class 08 diesel-electric shunter. In the real world, BR Class 08s were in fact the most successful shunting engines in the world with 996 of them built. Over seventy of them are preserved by heritage railways, such as the Dean Forest Railway and museums, such as the National Railway Museum. Around one-hundred BR Class 08s also remain in service on the national rail network. 08850, a BR Class 08 preserved by the North Yorkshire Moors Railway, appears in a Mr. Perkins' Railway segment.

'Arry, Bert, Splatter, Dodge, Paxton, Sidney, Ulli, the Mainland Diesels and Fernando are also based on BR Class 08s along with the international Brazilian, Indian and Chinese diesels. Two BR Class 08s also appear in The Railway Series.

Livery
Diesel is painted in the BR mixed-traffic black livery, 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 painted black.

Television Series

 * Season 1 - Wilbert and Tiger Moth (cameo) and Frank and the Trucks (cameo)
 * Season 2 - Skarloey and Rheneas Depart for Crewe (does not speak)
 * Season 3 - Cranky's Delivery and Diesel's Dilemma
 * Season 5 - Fergus' Market Day
 * Season 6 - Diesel Knows It All
 * Season 7 - Rails on Fire
 * Season 8 - The New Controller (cameo)
 * Season 9 - The Arlesdale Rumor and Railway Stowaway
 * Season 10 - A Normal Day for Dennis
 * Season 11 - Stepney and the Bluebell Branchline, Just Duck's Luck (mentioned) Spencer Goes Too Far (not named, mentioned) and Old Square Wheels
 * Season 12 - Greetings, Montague! (does not speak), Stafford's Electric Slide and Henry's Handcar Havoc
 * Season 13 - Sam I Am
 * Season 14 - Hatt Trick (cameo)
 * Season 15 - The Maron Station Makeover (does not speak), Nightmare on Sodor (fantasy), Ice Ice Daisy (cameo), Polar Express Coming Through! (cameo) and A Christmas Caroline
 * Season 17 - Unidentified Flying Scotsman, Tender Love and Care, Wellsworth the Wait (cameo) and Diesel Gets the Bronze

Specials

 * Thomas and the Storm
 * Sodor's Last Stand
 * Claw of the Law

Trivia

 * Diesel was the first diesel engine 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, Diesel 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.
 * 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 UK narration of the thirteenth series onwards and the US narration of the nineteenth series onwards, Kerry Shale gives Diesel a faint hoarse Cockney accent.
 * In the US narration, Michael Brandon gave him a gruff American accent & Martin Sherman gave him a gruff New Jersey accent.
 * In the Learning with Thomas segments Rob Rackstraw gave diesel a voice that sounds similar to Spud the Scarecrow from Bob the Builder, a series Rob Rackstraw has voiced in.
 * 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 Diesel 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.
 * Diesel had a total of sixteen facial expressions, one of which a weary face was never shown on-screen.
 * 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.
 * Additionally, Diesel refers to himself as "Diesel number one" during a parody of the Series 22-onwards intro sequence in the twenty-third series episode, Diesel Do Right.
 * The fifth series is the only series that Diesel does not appear in after his introduction in the second series.
 * Diesel is Ringo Starr's favourite character.
 * Diesel's normal horn sound was mistakenly reused for Salty in the eighth series episode, Percy's New Whistle and on the Diesel's Locomotion Mayhem ride at Drayton Manor Theme Park. It was also mistakenly reused for Mavis in the game Engines Working Together and on the Diesel's Locomotion Mayhem ride at Drayton Manor Theme Park, however her horn sound from Calling All Engines! can be heard when Every Cloud has a Silver Lining still plays there. It was also mistakenly reused for Bert on the Diesel's Locomotion Mayhem ride at Drayton Manor Theme Park, same with Dennis and Rusty. It was mistakenly reused for Paxton, but only in the fifteenth series episode Fiery Flynn. It was also mistakenly reused for Diesel 10 in Little Engines Easy Reading: Day of the Diesels in the mobile app, Read and Play!.
 * Diesel's horn sound used in some of his merchandise, Misty Island Rescue up to the fourteenth series and some games was reused for Mavis in the fifteenth series onwards (excluding the sixteenth series episode Thomas and the Sounds of Sodor). It was also reused for one of The American Diesels. It is actually a generic train horn stock sound effect and is used in many other pieces of media, such as Chuggington.