How the Diesel Stole Christmas is the 3-part 2013 Christmas Special. The three parts were uploaded on December 7, December 16, and December 24, 2013.
- Donald and Douglas
- Bill and Ben
- Arry and Bert
- Sir Handel
- Ivo Hugh
- Sir Topham Hatt
- Stephen Hatt
- Bridget Hatt
- Diesel 10 (appears as figure in Diesel's mind)
- Wretch (appears in flashback, does not speak, not named)
- Hiro (cameo)
- Stafford (cameo)
- Rheneas (cameo)
- Peter Sam (cameo)
- Rusty (cameo)
- S.C.Ruffey (singing only)
- Splatter and Dodge (original script only)
- Annie and Clarabel
- The Grinch (appears in pictures, does not speak)
- Scrap Engines (does not speak, appears in flashback)
- Bertie (appears in picture, cameo)
- Henrietta (appears in picture, cameo)
- Stephen (cameo)
- Salty (cameo)
- Toad (cameo)
- Horrid Lorry (cameo)
- Spencer (deleted scene cameo)
- Diesel: DarthWill3
- Lady and Paxton: Trevor O'Neal
- Edward and Bertram: EnterprisingEngine93
- Thomas: RightonTracks10
- Toby: James Riddle
- James: Andrew Homer
- Sidney: Connor O'Connell
- Duck: MallardFan62 (archive audio in first part)
- Oliver and BoCo: Knapford Productions
- Bill and Ben: CurtyLara2 (archive audio)
- S.C. Ruffey and Trucks Singing: Thurl Ravenscroft
- Everyone Else: Thomas1Edward2Henry3
- This special is obviously based on the book How the Grinch Stole Christmas by Dr. Seuss.
- This marks the first appearances of DarthWill3, Trevor O'Neal, RightonTracks10 ., Connor O'Connell, and KnapfordProductions as voice actors.
- This is the only time BoCo is voiced by KnapfordProductions, as he was just a temporary actor until a replacement for Tommy Davias was found, which turned out to be Andrew Homer.
- Bill and Ben's lines were recycled from Bill and Ben the Brave Brothers of Brendam because CurtyLara2 never responded to messages. The same thing applied with MallardFan8, but only in the first part. His lines were recycled from A Wretched Day for Henry and James and Gordon Goes Swimming. MallardFan8 was just having computer problems and the first part had already been uploaded by the time he had given the lines. To add to that, Rusty and Peter Sam were to have speaking roles but had to be made silent for the same reason.
- This marks the first appearance of SI3D's 2012 Thomas, Diesel, Annie, and Clarabel models, but only near the end.
- This special features music from Thomas and the Magic Railroad, Star Wars Episode II: Attack of the Clones, Doctor Who, and Inception as well as the famous song "Your a Mean One Mr. Grinch", written by Albert Hague and preformed by Thurl Ravenscroft.
- The regeneration of Diesel is obviously based on the regeneration idea from Doctor Who. In fact, the scene features a low pitch version of Vale Decem, which is heard during the 10th Doctors regeneration into the 11th.
- Gordon was originally going to have the role of Cindy-Lou Who, but the idea was dropped because of length issues.
- In the original script, Diesel 10 wasn't a figure in Diesel's mind. Diesel and his minions met him at Barrow-in-Furness as well as Splatter and Dodge to get equipment for their burglary. It was dropped because it didn't seem right to have these characters in real form, as they were only meant to be in Thomas and the Magic Railroad.
- In the original script, Diesel dressed up as Brick the Brickworks Engine from WildnorWester3D instead of Toby. This was changed for several reasons: No one would know who Barry is if they saw him (like Harold), Toby would be a more suitable disguise because of his boxy shape, and there was uncertainty that using an Asperger Syndrome Awareness character could promote controversy.
- Stafford and Stephen were supposed to have speaking roles, but Thomas1Edward2Henry3 forgot to film them.
- Stock footage from A Wretched Day for Henry and James is used as well as real pictures from Thomas and Percy's Christmas Adventure, Trouble in the Shed, Thomas' Christmas Party, It's Only Snow, Edward, Gordon, and Henry, Thomas and the Missing Christmas Tree, Escape, Not So Hasty Puddings, and the Railway Series book Stepney the Bluebell Engine.
- The drawings during the title sequence were drawn in Microsoft Paint.