Spencer is a sleek tender engine. He is owned by the Duke and Duchess of Boxford. He is a silver engine that has his own coach to carry the Duke and Duchess of Boxford. And also pulls his own furniture car.
During his first visit to Sodor, Spencer took the Duke and Duchess of Boxford on a trip around Sodor. He ignored Gordon's warnings about taking on water and thus ran out on his hill; however, he blamed the incident on a leaky tank, and had to rely on Gordon to take him to Maron.
Upon his next visit, Spencer challenged Edward to a race and maintained a lead for the majority of the race, but vainly fell asleep while the Duke and Duchess stopped to take photos and lost to Edward, after Edward got onto the summer house branch line first.
Spencer has since developed a rivalry with Thomas, with the latter often trying to outshine Spencer - largely without success.
Unfortunately, Gordon is coming down the line and does not see the Troublesome Trucks and crashes into them. The trucks zoom away and now Spencer has learnt his lesson.
In 2008, Spencer is ready for competition and challenges Gordon to a race leading disastrous results.
Spencer returned to Sodor to help build a new summer house for the Duke and Duchess of Boxford, much to the annoyance of all the engines. First, he insulted the other steam engines - especially Thomas by calling him a "toy tank engine", which as a result they had a competition of strength. However, Spencer neglected to build the new summer house when he became suspicious about Thomas, thinking he was being a tricky tank engine and ended up getting slate down his funnel at Sodor Slate Quarry. When Spencer discovered Percy's mail vans (thinking that Thomas was hiding them from Percy), he got into trouble with the Fat Controller, who thought that Spencer was hiding the mail coaches all the time. Afterwards, Spencer lost his pride when his owners turned up for their holiday. He then got stuck in the mud when he chased Thomas to Knapford. After being rescued by Hiro, Spencer apologised to Thomas and Hiro and they all worked together to finish the summer house.
Sir Robert Norramby borrowed Spencer as his private engine during the restoration of Ulfstead Castle. He transported the Earl around and much to his embarrassment, had to pull some stones for the job. During that time, he attempted to have races with Gordon, but when the two met Connor and Caitlin during one of their runs, they called off the race. After the restoration was complete, Connor, Caitlin, Gordon and Spencer had another race from Ulfstead's grounds.
Spencer teased Stephen for being too slow and Stephen is determined to prove him wrong. Later, when Stephen is pulling jam, Spencer is there and Stephen tells him to push and Spencer was cross when Stephen recklessly insulted him. He pushes him Ulfstead Castle, but stops him would causes Stephen to crash and is scolded by Sir Robert Norramby.
Spencer brought a VIP from the Mainland to present the Fat Controller with an award. Due to showing off, he ended up on Edward's Branch Line. Once he finally arrived at Knapford, the Deputy Minister crossly announced that he would not travel back to the Mainland with Spencer. Throughout the day, as the other engines were showing off, Spencer felt sorry for himself and wished he had done his work properly. He learned from his mistake and successfully brought the Deputy Minister back to Sodor the following day.
In 2011, he turns against the other steam engines and joins Diesel 10 but after runs out of coal, Diesel 10 betrays him making it so neither the steam engines or the diesels like him.
One day, Spencer was travelling through Henry's Tunnel and almost ran into Thomas, who was hiding in the tunnel pretending to be a made-up engine called Geoffrey, to trick the Fat Controller. At winter, he had to stay on Sodor because the Vicarstown Bridge was blocked with snow. He teased Henry by telling him he might see an abominable snowman. But when the two engines saw something covered in snow walking towards them, Spencer tried to run away, but his valves became blocked. Luckily, it was only the Fat Controller, who had gotten into trouble in the snow. Later, Spencer had to take the Duke and Duchess to Callan Castle, when his valve gear had snapped and broke down, so Thomas, Bertie and Harold had to take the Duke and Duchess to Callan Castle instead.
Spencer would then go on to participate in The Great Railway Show where he served as a UK representative and competed in The Great Race event against Gordon and Flying Scotsman, as well as Axel and Etienne. He came in second place, narrowly losing to Etienne.
Spencer is painted the LNER's silver with black lining.
- Season 1: Toby and the New Engine and The Trouble with Spencer
- Season 2: The Daring Duel
- Season 4: Spencer's Generous Deed
- Season 7: The End of the Track
- Season 8: Sir Spencer of Sodor
- Season 11: Around the Railyard in 64 Seconds, The Great Western Way (cameo), Spencer Goes Too Far and Old Square Wheels (Mentioned)
- Season 12: Greetings, Montague! (mentioned).
- Season 13: Duck and the Quack Attack (cameo), Ivo Hugh's Day at the Zoo (mentioned) and How Gator Stole Christmas (cameo)
- Season 14: Millie's Castle Hassle, Henry Gets Stumped, Hiro and the Heat Wave (cameo) and Dirty ‘Arry.
- Season 15: Flash Gordon and Toby's Turntable Fable
- Season 16: Finding Lorry (cameo)
- Season 17: Bold Slow Coach, Sidney Transplant (cameo), Diesel Gets the Bronze, Toby, Or Not Toby (cameo)