Duncanis a yellow narrow gauge tank engine. He is named after the Arlesdale Railway's controller, Mr. Fergus Duncan. He is good friends with Sir Handel and has a twin at the Talyllyn Railway named Douglas and is known to "rock 'n' roll".
Duncan is a yellow narrow gauge tank engine that works on the Skarloey Railway,he had many adventures like pushing Rickety up the Quarry Mine Tunnel,shunting trucks into a goods train and taking them up Gordon's hill,we first met him in "Home at Last",which is not one of the Thomas The Tank Engine and Friends Wooden Railway Adventures,but we also met him in some wooden adventures.
- Season 1: The Trouble With Trucks (does not speak)
- Season 2:
- Season 3:
- Season 4: Rickety's Revenge, Clumsy Culdee
Season 12: Rheneas and the Risky Rendezvous
Season 13: Ivo Hugh's Day at the Zoo (does not speak)
Season 14: Millie's Castle Hassle (does not speak)
- Since to Duncan's rock 'n' roll, he sometimes derails on bumpy lines.