Mallard is the world's fastest steam engine, holding a speed record of 126 mph. He is most of the time a very popular exhibit at the National Railway Museum in York and is very well looked after. He is 1 of 6 surviving A4s. He was brought to The Island of Sodor to cover Gordon's job of pulling the express, but does come to Transportainia on occasion to help with express runs.

Mallard, being one of the fastest and smoothest engines in the world, tends to be smug about it, much like his brother Spencer and nothing like his elderly sister Olwin. While he does work on Sodor most of the time, he is sometimes brought to Transportainia to help cover one of the express trains usually pulled by either Gordon or Montana.

His voice source is freelance, so long as it’s within the age range (Middle Age) (though I'd recommend British/English for the accent).