Murdoch is one of Sodor's largest and strongest engines.
Murdoch was brought to relieve the engines of their heavy workloads. He was big and strong, so the other engines were eager to learn more about him. Murdoch, however, disliked the noise of their chatter and got cross with Salty and Harvey when they inquired about his past exploits. The next day, Murdoch finally had a chance to pull a train through the quiet countryside, but his journey was interrupted by a flock of sheep. Murdoch had to wait with the noisy sheep until Toby could bring the farmer to lead them away. That night, Murdoch found Salty's and Harvey's company a relief.
Murdoch was happy but shy about being decorated for the May Day festivities.
On one windy autumn day, a large red carpet landed on a goods wagon from Murdoch's goods train, unbeknownst to Murdoch. Percy briefly chased after it, until the heavy winds blew it away again.
Emily once needed Murdoch's help when she became stranded in the mud, and near the end Emily asked him which track should she take. Murdoch told Emily that the tracks on Gordon's Hill were being cleared and told her to take the valley route instead.
Murdoch shunted Rocky while helping Thomas recover the lost materials for the Sodor River Bridge's restoration.
Murdoch is a mighty, powerful engine with ten drive wheels. He is one of the largest engines working on Sodor and was brought to the Island to help with the heavy workload and pull heavy goods trains across the Main Line. Murdoch is as shy as he is strong, as he is actually a gentle giant. He can often be found seeking peace and quiet, away from the bustle of the yards and the Docks. He enjoys long hauls through the countryside and, although he can get short of patience and a little annoyed if he does not get some alone time, he can be quite a reserved engine. Although he can be an independent worker, Murdoch is often content to join in, help, and offer advice where he deems it worthy, but, despite being hard to miss due his defining strength and size, he will not jump to put himself at the centre of attention.
Murdoch is a BR Standard Class 9F used for fast and heavy goods trains. The class was the last of the BR Standards, and the final steam engine class built by British Railways, with the last one, "Evening Star," built in March 1960. "Evening Star" and eight other 9Fs are preserved. One 9F, "Black Prince" holds the record for hauling the heaviest steam-hauled train in Great Britain, at 2,198 tons. Marie is also a member of this class.
Murdoch is painted orange with green and red lining. He has smoke deflectors, on which he wears red nameplates with gold lettering.