This list is for characters who appear in the television series but only for one episode or in flashbacks, listed in chronological order.

Sir Nigel Gresley


Sir Nigel Gresley appeared in the episode Old Rivals where he appeared as a visitor to Euston. He was very rude and angry at the LMS territory. Fred tried to talk to him but he said nothing, let out steam loudly and rolled out of the sheds.



Mallard appeared in the episode Old Rivals when the Duchess was telling the story of the competition between the Big Four Railway Companies. She was kind and said that this was a record for steam, and not her class.

Flying Scotsman

Flying Scotsman appeared in the episode Old Rivals, where he arrived at Euston after taking a train. He initially felt uncomfortable in the yard and didn't interact with William. But after the engines showed him compassion and kindness he talked happily to them like they were old friends. He left after being cleaned. William later revealed that he was Flying Scotsman, leaving everyone in shock.
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Sam is a 7F who worked on the Somerset and Dorset Railway with Ivatt. Not much is known about Sam, but he shares the same class as Rob.


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"Tornado" appeared in the episode Arthur's Tale, where he was on a passenger train at the 1948 exchange trials. He was a kind engine and made good friends with Arthur.

Despite being built in 2008, Tornado was the only Peppercorn A1 model David C.G. had at that time. So his model was used instead.


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Merlin appeared in the episode Arthur's Tale where he arrived one day at Euston during the 1948 Exchange Trials. He could not pull the train back home due to burning bad coal and Arthur had to take over. He was not named in the series but his number and Experimental Livery showed that he was indeed Merlin.



Spammer appeared in the episode Double Trouble. He was waiting for William as the latter was late. He was annoyed with William for this. He was hauling 2 blood & custard coaches.


Arnold appears a lot throughout the series, at the sheds and other places. He lives in a rundown shed in the outskirts of London, where Vick used to stay. His number is 92044. When Horwich was at Crewe, his model appears on the scrap siding, and is in the line of scrapped engines who are implied to be dead.



Britannia appeared in the episode A Reverend and a Metrovick where he was one of the engines who grumbled at Vick for breaking down at points saying that he and the other "stupid diesels" are making the railway worse by causing traffic. His name was not mentioned in the episode but his nameplate clearly read Britannia confirming his identity.



Kentish has been seen several times throughout the series. He was one of the engines allocated to Vick's old shed. He was also one of the engines who heard about Horwich and was felt positively about him getting a new job. He then appeared in the episode Babs and Seraphim as a visitor to the sheds and in No Identity where he reunites with Dominic.


The Unnamed Standard 3


This Unnamed Standard 3 was first seen at Euston station. He was seen again when he had taken the Rev. W. Awdry on a rail tour the previous day and as a thank you, Awdry offered to clean the engine. He was seen again when Horwich stopped at a station on his way to Crewe Works. He was once allocated there but was then reallocated to Birmingham. He also advised Horwich to turn back from Crewe as it was no longer the safe place it used to be.



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Sixteen was intended to appear in the episode A Reverend and a Metrovick but was cut from the script for reasons unknown. He first officially appeared in the episode The Sad End to the Musbury Vale Branch . He was the originally the quarry engine near Musbury Vale. Though he was unnamed in the episode David has made it clear it was indeed Sixteen.


D326 was a friend of Vick. He was involved in the infamous "Great Train Robbery". He was mentioned only once by Vick in the episode John, Vick & the Great Train Robbery.

Donald and Douglas


Donald and Douglas have appeared several times in the series as cameo appearances and in separate episodes. Douglas appeared in Babs the Brave hauling some freight trucks.

They were fully introduced on the second short of the series, The Third Anniversary Special. Here they were seen at a confrontation between Richard and Roger but eventually mended ties.



Mavis is a female Diesel engine who works for the Ffarquhar Quarry Company on the Island of Sodor. She made a cameo appearance in The Sad End to the Musbury Vale Branch.


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"Devious" Diesel is a devious black diesel shunter. He first appeared in the episode Festive Spirit where he was briefly seen pulling a train. He appeared once again during the episode The Sad End to the Musbury Vale Branch where he was seen shunting at the yards in place of Den while he was shut up. Diesel appeared once again in the episodes Crewe and An Anxious Wait where he was seen in the former shunting Horwich off to the sheds and he was about to make another move in the latter episode but was rebuked by Fred and quickly raced away.



Basil is a class 47 Brush type diesel who first appeared in the episode Crewe, having derailed outside the yards. he was then fully introduced in An Anxious Wait. He was very rude and impolite to both Horwich and John. but was quickly silenced after Fred arrived and entered the conversation.



Seraphim is a rude and pompous engine who arrived as a visitor to the sheds. She was very high strung and boastful. Babs used to adore her beauty but her opinion soon changed thanks to her attitude. She eventually got her comeuppance when she broke down and Horwich and Fred took over her train.

Engine 17

This article is about the character. You may be looking for the episode.
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An experimental engine built during the war (WW1) around the same time as Simon, Engine 17 was declared a failure and would not steam properly. He was a reckless engine who said he always deserved better. Reckless as he was, one night he threw his driver and fireman out of the cab and ran out onto the mainline before being hit by the post train. Engine 17 was completely destroyed and barely anything remained of him, whatever remains that were left were scrapped. He first appeared in the episode Engine 17 where he began haunting the engines of Euston. After scaring Terry, Horwich, Ivatt and Jimmy, Fred comfronted him and demanded he never to come back. But Engine 17 didn't listen. And at the end of the episode, he was seen again outside the sheds. He shares a similar design to Thomas.




Dominic was sent to Euston to help out due to the Coal Mine Strike. He wasn't named at first. Dominic lied to Babs that he worked in New York City in America and to Horwich that he was chased Indians on horses every day. When the Euston engines comfronted him about it he admited to having "No Identity" before being named Dominic, and later returning to his own shed on good terms.