Duck (formerly known as "Montague") is a loyal and hard-working Great Western Railway 57xx 0-6-0 Pannier Tank engine. He believes that there are only two ways of doing work: the "Great Western Way" or the "wrong way." He was brought to the Island to help Percy with his shunting. He was the first engine to realize Diesel's evil intentions, and was temporarily sent away due to him. He was brought back after Diesel was sent away.
- Duck got his nickname from his supposed "waddle," which was due to his uneven wheels.