- "Keep in mind i'm a little harder on the other engines than I am on you Culdee. It's because you keep a level smokebox and I trust you the most."
- ―Walter Richards, Culdee Fell
Culdee is a purple mountain engine named after a mountain called Culdee Fell who works on the Culdee Fell Railway.
Culdee was sent to the Works in the Mainland many years ago and on his way back he stopped to talk to the Skarloey Engines. He told the curious engines about his mountain railway and his various experiences.
There he dealt with the likes of Sir Handel and Duncan by telling a grim tale about Godred, a swanky mountain engine who fell off the mountain and was taken apart for his actions! That shut the two naughty engines up for a time!
Culdee was later putting off taking a crew to a bridge inspection, but after a talk with Gator, he quickly went to work. However, he later had an accident, falling off the bridge he was heading to due to damaged track. He landed on a raft and stayed afloat for some time, but he eventually sank into the raging waters, and was found on the shores of Poll-ny-Chrink, critically damaged, though how he ultimately survived was unknown to him, as his initial fall should've been enough to smash him.
Culdee's repairs took several months to complete, and the accident traumatized him, as he refused to speak about the incident to Victor or any of the workmen at Crovan's Gate, in addition to suffering from nightmares. When Derek came to pick him up, Culdee had a little chat with the diesel concerning his work on the mountains, but he wasn't really looking forward to going back to work.
He later received a pep talk from Walter Richards, who explained his faith in Culdee before informing him of having to continue where he left off; track maintenance. Nervous, Culdee headed up the line with Catherine, and after some prodding, revealed the details of his accident. Upon learning that a shepherd was dangling off of the very bridge Culdee himself had fallen off of, Culdee immediately retreated back to the stations. Despite urging from Catherine and the other mountain engines, Culdee was still too scared to go back up. However, the arrival of Percy, who explained all that he had learned from Gator, and his own personal fears of the expanding world, helped Culdee get his confidence back. Filled with a new determination, Culdee went back up the line to rescue the shepherd.
- Season 0: Old Groaner (cameo)
- Season 1: Rendezvous with Disaster
- Season 2: Rock-Star (cameo), Swashbuckler (cameo), Thomas and the Fortune Teller (cameo)
- Season 3: Logan Leaves his Mark, Culdee Fell, Derek and the Two Faced Engines, Penn Pals (cameo)
- Web Clips: Thomas the Tank Engine 70th Anniversary Celebration! (cameo)
- From Swashbuckler onwards, his 2005 model was used. All previous appearances used his older model. His old model went to become Shane Dooiney.
- Culdee gained a Swiss accent in "Logan Leaves his Mark", reflecting his basis' origins.