Luke is a plucky little green tank engine on the Skarloey Railway, brought to Sodor from Ireland. For a long time, he hid in fear and deep shame in the tunnels and caverns of the Blue Mountain Quarry from a terrible, dark secret, believing that he had caused a yellow engine to fall into the sea. Fortunately, he befriended and trusted Thomas, who investigated and realised the yellow engine was Victor and that the accident had not been Luke's fault, managing to clear his name. Luke is a gentle, sensitive soul and is bubbling with enthusiasm, keen to work as part of the team. Like many engines, there are times when he may want to run away and be left alone and he may not be quick to stick up for himself either, but when there is someone in need, Luke is passionate about showing how much he values his friends and will bravely heave into action without second thought.
Luke is painted pea green with white lining. His name is painted in white on his tanks and he has brass and black number plates on both sides of his cab.
- He and Peter Sam are cousins.