Duncan is a narrow gauge engine from The Island of Sodor.
If there is one engine on the Crotoonian Hills Narrow Gauge Railway to take caution of, it's Duncan. Infamous for his bad temper and gruff attitude, Duncan is tough, rude, and a funnel-full of trouble on a bad day. Though he does mean well, he tends to be rough with his work and get himself into trouble while on the job. He can haul fifteen slate wagons at a time, and derail them in the same afternoon if things go wrong.
Duncan is based on the Talyllyn Railway's Douglas, an Andrew Barclay "E" or "Light" Class 0-4-0WT. This engine is currently selected to be dressed up as Duncan on special events associated with the "Thomas the Tank Engine" franchise, known as "Duncan Days". Several other engines of this class are also preserved.
Duncan is painted golden yellow with black lining and gold boiler bands. He also wears a brass (originally black) nameplate on either side of his boiler, and a black numberplate on each of his coal bunkers.