Diesel 10 is a villainous diesel engine with a hydraulic claw fitted on his cab roof, which he has affectionately called "Pinchy". Ever since he arrived on Sodor, he has been determined to make the steam engines' lives as miserable as possible, and is known as one of the most ruthless and horrid engines on the railway.
Diesel 10 had previously visited the Island of Sodor years ago, and caused several problems for the steam engines while he was there. During his visit, he found Lady, the engine responsible for keeping Sodor alive, and he chased after her in an attempt to destroy her. In the ensuing chase, Lady's driver, Burnett Stone, used up all her coal and made her go too fast, and Diesel 10 crashed her. Burnett survived the whole ordeal and took Lady back to Muffle Mountain to be restored, but he lacked the coal necessary to make her steam.
Years later, Diesel 10 returned to Sodor when the Fat Controller was on holiday, with the intention of destroying Lady once and for all. He brought his two lapdogs, Splatter and Dodge, with him, and caused many problems for the steam engines, such as dumping sneezing powder around the sheds. He later destroyed the scaffolding that had been erected beside the shed, and taunted Mr. Conductor over his lack of gold dust.
The next day, Mr. Conductor went on a journey to the windmill, but got lost along the way. Diesel 10 found him roaming alongside the track and picked him up with his giant claw, threatening to drop him in the river below the viaduct if he did not tell him the location of the Magic Buffers. However, Mr. Conductor had a pair of wire cutters on hand and used them to cut the hydraulics to the claw, causing Diesel 10 to fling him across the Island and right at the windmill; he defended his actions to Splatter and Dodge, claiming that he was trying to see if Mr. Conductor could escape, and covered himself in coal dust when he hit a hopper.
When Junior mistakenly landed on his cab, Diesel 10 raced across the Island and came to a stop at the Scrapyards, throwing Junior onto James' cab. Diesel 10 cornered the two near a pair of broken buffers and threatened to push them into the melting pit, but Junior used the last of his gold dust to teleport him and James out of the Scrapyards.
Diesel 10 later found out that Lady had been restored, and he chased her, Burnett and Thomas across the Island to destroy them. As the engines approached the collapsing viaduct, Lady and Thomas managed to get over the bridge safely, but Diesel 10 was too heavy for the rails and fell into a river barge filled with sludge, putting an end to his diabolical plans. After this incident, Diesel 10 was sent away in disgrace. (Film; Thomas and the Magic Railroad)
Personality and Traits
Behind the Scenes
- Rupert Degas was previously cast for the role of Diesel 10 in Misty Island Rescue. However, he was replaced by Matt Wilkinson as the voice directors felt his voice did not suit the character. 
- Diesel 10 has never been seen pulling any sort of rolling stock.
- Up until the seventeenth season, Diesel 10 had only appeared in specials and films.
- Diesel 10 is only ever referred to by name in his debut scene in Thomas and the Magic Railroad; throughout the film, he is referred to as "Diesel".