The LMS Fairburn Tank 2-6-4T is a class of steam locomotive. They were designed by Charles E. Fairburn. 277 of these locomotives were built between 1945 and 1951, numbered in the range 42050-42186, (4)2187-(4)2299, (4)2673-(4)2699.

This design was based on the earlier Stanier LMS Stanier 2-6-4T, which was derived from Henry Fowler's LMS Fowler 2-6-4T engine. Fairburn modified the design to have a shorter wheelbase, allowing curves of 5 chains to be negotiated; to reduce the locomotives mass per unit length the overall weight was reduced. It was also the basis for the later British Rail Standard Class 4 tank.

The class was withdrawn between 1961 and 1967. Two of the Brighton-built locomotives have survived in preservation.