Spencer is a streamlined engine from the Mainland near Sodor.
The Duke and Duchess of Boxford's private A4 engine, Spencer is often lent to the higher ups in Crotoonia, like Sir Allen Featherington, Ariel and Eric, or sometimes other Crotoonian visitors, like Elsa and Anna of Arendelle. Spencer often likes to think he's one of the finest steam engines in the world, and usually tries to prove it to the other Crotoonians....usually ending up in cinders and ashes! Spencer likes to show off his speed and strength to the other engines, but most of them usually don't care, as they want to keep the work in Crotoonia flowing smoothly! Spencer is known to have a rivalry with Farnsworth, which always results in a race when the two are around!
Spencer is based on an LNER Class A4 Pacific. Olwin from Chuggington and Mallard, holder of the world speed record for steam locomotives, are other members of this class. An additional five members of this class survive in preservation.
Spencer is painted metallic silver, still with black lining. He has red nameplates with his name in gold on the sides of his boiler. His livery may have been inspired by that of the first four A4s, which were painted in a "silver" livery.
- His model is a ripped model from the 'Hero of the Rails' game for the Nintendo Wii and DS, Though With Moving Eyes.