The engine on the bridge
The ghost engine (called Zachary) was a narrow gauge engine who supposedly worked on the Skarloey Railway. According to Rusty, he was returning home one misty full moon when he lost control and fell into a ravine. No one has ever found him, and it is unkown if he is dead. But workmen claim to have seen his ghost trying to cross the ravine, only to fall.
Rusty told Duncan his story after he teased Peter Sam for allowing his trucks to derail in the ravine. Duncan disbelieved the story, but the next day Duncan's crew arranged things so that Duncan believed the engine was trying to cross the bridge at the same time as him, and quickly ran back.
Basis
Zachary uses Skarloey's model and Percy's whistle.
Appearances
Zachary only appeared in the fifth season episode "Duncan gets Spooked".