Devious Diesel is known by everyone as the secondary antagonist in Thomas the Tank Engine & Friends. As a villain, he is oily, malicious, devious, scheming and full of ideas to get revenge. But from Season 10 and onwards, Diesel shows that he actually does have a good side in him, but one would still have to look deep to find it. As a hero, he wants to try to prove himself Really Useful, but instead he usually acts more like a school yard bully and still hates steam engines, much to the annoyance to Thomas fans. It can be possible that Diesel is a permanent resident of Sir Topham Hatt's railway since Season 8.
Diesel is based off a BR Class 08 Diesel Shunter, like 'Arry, Bert, Paxton, and Sidney.