Stephen was built in 1829 by Robert Stephenson and competed in a series of races against other engines, which he ended up winning at. He used to work in mines and at harbours, but as newer and faster engines were being built, Stephen was abandoned until he was uncovered by Sir Robert Norramby and brought back to Sodor, where he was overhauled at the Sodor Steamworks.
Norramby had Stephen restored so that he could take tourists around the castle grounds; however, Stephen was not aware of this and after being told by Thomas that the Earl had a surprise job for him, became too excited to wait and travelled around Sodor, looking for jobs that he could do. However, Stephen proved to be too weak and slow for most of the jobs and after visiting an abandoned mine, became trapped after having to avoid a runaway train from running into him. While he was in the mine, Stephen managed to uncover King Godred's long lost crown and after being rescued, he was given a new funnel and was present at the grand opening of Ulfstead Castle.
When James was trying to scare Percy, Stephen accidentally fell into the moat at the castle when he became scared by one of James' tricks. He and Percy both had the last laugh after they successfully frightened James. Later, when Percy was having a day of bad luck, Stephen gave him his lucky horseshoe to help him feel better, but Percy lost the horseshoe before he could leave the castle. He was later chosen to collect the ingredients for the Earl's afternoon tea, but spilled the barrels of jam when he came into the castle too fast. Fortunately, Stephen managed to amend his mistake by having the afternoon tea on a train around Sodor, which proved to be popular.
When the Earl was expecting a shipment from the Mainland, both Stephen and Millie waited for the shipment to arrive, when they saw Marion running away from the dinosaur models that Samson was delivering, which turned out to be the Earl's important shipment.
Once, as he was taking tourists across the island, Stephen noticed that the Sodor Suspension Bridge was falling apart. He got his passengers to safety, then managed to stop Gordon and the express from crossing the bridge, seconds before the bridge collapsed.
When the Great Railway Show was being held on the Mainland, Stephen was taken to the show along with the other Sudrian engines who would be competing. He took the Sodor Brass Band and other visitors around the shunting yard as the show was happening.
In the twentieth season, Stephen has a race with Glynn during the Christmas holidays.
Stephen is a jolly old engine with a positive attitude and a good sense of humour. He is a good-hearted and quick-witted engine and will not take any nonsense from engines like Spencer or Diesel. Some of the smaller engines look up to him for advice and he is always willing to get the job done.
Stephen is based on Stephenson's Rocket. Though his design is based on the post-Rainhill modifications, Stephen has identified himself as the original Rocket, describing the Rainhill trials and his subsequent working years.
Stephen is painted golden yellow and black. He carries a gold nameplate reading "Rocket" on each side of his boiler and his domes, whistle, exhaust pipes and boiler bands are painted bronze. During his early years and after his overhaul, Stephen had a plain black funnel, but after he was rescued from the mine, his funnel was painted white with a gold finial.
Prior to being overhauled, Stephen was painted brown with black wheels. Due to being abandoned for so long, he was covered in patches of rust.
- Season 17 - The Lost Puff, The Phantom Express, Percy's Lucky Day, Too Many Fire Engines, Santa's Little Engine and The Afternoon Tea Express
- Season 18 - Marion and the Dinosaurs, Samson at Your Service (cameo) and Millie and the Volcano (cameo)
- Season 19 - Slow Stephen
- Season 20 - The Christmas Coffeepot
- 2013 - The Lost Puff and Too Many Fire Engines! (speaks in speech bubble only)
- 2014 - The Afternoon Tea Express and Percy's Lucky Day
- 2015 - Marion and the Dinosaurs (speaks in speech bubble only)
- Bob Golding (UK/US; King of the Railway onwards)
- Rainer Schmitt (Germany; King of the Railway only)
- Till Huster (Germany; seventeenth season onwards)
- Atsuhiko Nakata (Japan; King of the Railway theatrical version only)
- Nobuaki Kanemitsu (Japan; King of the Railway Netflix version onwards)
- Stig Krogstad (Norway; King of the Railway only)
- Øyvind Borgemoen Lyse (Norway; seventeenth season only)
- Piotr Warszawski (Poland)
- Eduardo Fonseca (Latin America)
- Paul Disbergen (The Netherlands)
- Juan Navarro Torelló (Spain)
- Denis Bespalyy (Russia; King of the Railway onwards)
- Stephen does not have chains for either his front or rear coupling.
- In the seventeenth season episode, Percy's Lucky Day, it is revealed that Stephen has a lucky horseshoe resting on his exhaust pipe.
- In both his Take-n-Play and Wooden Railway merchandise models, his tender is unremovable to detach him.
- Most merchandise lines show Stephen carrying the Ulfstead Castle crest on his tender, but he does not carry this crest on his tender in the show.
- Stephens Take-n-Play and Wooden Railway prototypes have a cab. However, he does not have one in the television series.
- In the Polish narration, Stephen's name is Sławek, which is also Skarloey's name in the same narration.
- Stephen's name is more than likely derived from his builder, Robert Stephenson.
- Originally, after his restoration, Stephen would gain a cab. In fact, some merchandise prototypes depict him with a cab.
- Stephen has gone through a few changes since his introduction:
- When he was restored, he gained a lamp and front coupling.
- In the nineteenth season, he gained a tail lamp.
- Percy: Did you ever see knights in shining armour?
- Stephen: No! I may be old, but I'm not that old! And before you ask, I never saw dinosaurs either!
- Percy and Stephen discussing the latter's age, King of the Railway.
- Spencer: The visitors will wait a long time for their afternoon tea if Stephen is doing the job.
- Stephen: I'll have you know they use to call me the Rocket, because I was so speedy!
- Spencer: Pah! Compared to a horse and cart maybe!
- Spencer insulting Stephen, "The Afternoon Tea Express", seventeenth season.
- Millie: Looks like someone is back to her old self.
- Stephen: Yes Marion certainly isn't scared of dinosaurs anymore, in fact you could say she really "Digs" them!
- Millie and Stephen talking about Marion, "Marion and the Dinosaurs", eighteenth season.
He plays Robin Hood as a Stork in Rayman Hood (ThomasTenCents34526's Style)
- He is Robin Hood as a stork in disguise.
- Wooden Railway (normal, rusted, royal bunting and mine dust covered versions)
- Motor Road and Rail
- Motorized Railway
- Take-n-Play (normal, rusted, dust covered and talking versions)
- Minis (classics, dino and DC super friends)
- Mega Bloks
- Thomas and Friends Adventures (coming soon)