Xavier and Xander are a pair of diesels that are permanently coupled together.
Xavier and Xander were brought to Sodor to help with heavy goods trains.
Xavier and Xander are based on a BR Class 13. The type was designed in 1965 because of the need to provide more powerful shunters for the Tinsley Marshalling Yard. Because of Tinsley's status as a hump yard, it was not possible to use a single locomotive owing to the risk of grounding. So, to achieve the required power, a pair of Class 08 shunters were permanently coupled in 'master and slave' formation, with the slave unit having had its cab removed. Only 3 Class 13s were built and all 3 were scrapped
Xavier and Xander are painted in two tone blue with yellow and black warning stripes on their backs. Xavier has yellow on his front while Xander has black. They both also have yellow coupling rods.