Duncan the "Rock 'n' Roll" Engine is a yellow narrow gauge tank engine. He is number 6 on the Skarloey Railway. Duncan keeps busy and means well, but is also bouncy and rude. He has been known to sing and sway and swivel around, which his driver calls "rock 'n' roll".
Duncan has 4 roles:
- Mortimer Mouse (Mickey Mouse)
- Happy (Snow White)
- Nuka (The Lion King 2: Simba's Pride)
- Chi-Fu (Mulan)