The GNoSR Classes X and Y were two similar classes of 0-4-2T steam locomotives built by Manning Wardle for the Great North of Scotland Railway. The two classes were similar, and were used throughout their lives to shunt on the docks at Aberdeen. They passed to the London and North Eastern Railway at the 1923 grouping, and received the LNER classification Z5. The class X were later reclassified Z4.