The New Adventures of The Narrow Gauge Engines is a fan-fiction spin-off series of Thomas the Tank Engine and Friends. It stars the narrow gauge engines. Each season will have 22 or 24 episodes.
- Skarloey is an old and red engine and the main star of the series.
- Rheneas is Skarloey's best friend.
- Sir Handel is a grumpy blue engine. He is considered as an Anti-Hero.
- Peter Sam is a happy green engine.
- Rusty is an orange diesel engine. He's a good friend to Skarloey and he has a love/hate relationship with Duncan.
- Duncan is a stubborn yellow engine. He is also considered as an Anti-Hero. Also, he and his haft-brother Smudger always get into arguements, and he and Sir Handel get into bad things too.
- Fearless Freddie is an old warhorse engine.
- Ivo Hugh is a red tank engine, as well as Freddie's brother.
- Duke is an old tender engine.
- Mighty Mac is a double-ended Fairlie engine.
- Bertram is an old engine and Duke's twin.
- Smudger is the main antagonist. He is also Duncan's haft-brother.
- Stanley (aka No. 2) is Smudger's best friend. Together, they cause a lot of trouble.
- Proteus is a yellow engine with a very bright light.
- Fred is a lazy diesel engine.
- Mr. Percival is the controller of the railway.
- Thomas is a blue tank engine. He's a great friend to the narrow gauge engines.
- Henry is a big green engine and Peter Sam's best friend.
- Gordon is a big blue engine and Sir Handel's best friend.
- James is a red tender engine and Duncan's best friend.
- Ada, Jane and Mabel are open coaches.
- Agnes, Ruth, Lucy, Jemima are narrow gauge coaches.
- Beatrice is a guard's van.
- Cora is a tool van.
- Gertrude and Millicent are two other narrow gauge coaches.
- Colin is a crane who lives at the wharf
- Madge is a snub-nosed lorry. She and Henry are in love.
- Keith Wickham - Skarloey, Sir Handel, Peter Sam, Duke, Bertram, Henry, Gordon and James
- Ben Small - Rheneas, Proteus, Fred, Smudger, Stanley, Ivo Hugh and Thomas
- Michael Angelis - The Narrator
- Martin Sherman - Thomas and Ivo Hugh
- Ben Small - Rheneas, Proteus, Smudger and Stanley
- Bob Golding - Freddie, Duke, Bertram and Fred
- Kerry Shale - Henry, Gordon and James
- Michael Brandon - The Narrator
- Skarloey Helps Out - Skarloey must help Duncan when he crashes into an old barn.
- Sir Handel & The Trucks - Sir Handel gets cross when he has to work with troublesome trucks at the quarry.
- Thomas & Skarloey vs. Smudger & Stanley - Smudger and Stanley try to take over the railway. Can Thomas and Skarloey stop them?
- Henry & Peter Sam - Henry wants to give Peter Sam a tour of the standard gauge railway.
- Freddie Takes Charge - Freddie show Mighty Mac how to work the coal yard.
- Rusty The Really Useful Diesel - Sir Handel and Duncan say the Rusty is useless. But soon, Rusty proves how he is really useful.
- Duke, Bertram & The Birthday Train - Duke and Bertram are chosen to pull the birthday train to Mr. Percival's birthday party.
- Skarloey & Fred - Skarloey meets a new diesel named Fred. Fred is lazy and won't work with Skarloey. Can Skarloey get Fred to do work?
- Proteus' Bright Lamp - Peter Sam thinks Proteus' lamp is silly. But one night, when Peter Sam gets lost, Proteus finds him with his bright lamp.
- Sir Handel's High Speed - Sir Handel tries to be the fastest narrow gauge engine in the world.
- Rheneas & The Forest - Rheneas has to make some nighttime deliveries, but he has chuff through the forest, which looks scary at night.
- Ivo Hugh - An engine named Ivo Hugh arrives on the railway. And Freddie thinks that Ivo Hugh is replacing him because he is also number 7.