The London Midland and Scottish Railway's class 8F is a class of steam locomotive designed for hauling heavy freight. 852 were built between 1935 and 1946 (not all to LMS order), as a freight version of William Stanier's successful Black Five, and the class saw extensive service overseas during and after the Second World War.

On the outbreak of the Second World War, the design was chosen to become the country's standard freight design, reprising the role the GCR Class 8K had in the First World War. The War Department had 208 8Fs built by Beyer Peacock and North British Locomotive Company and requisitioned 51 more. Stanier 8F production for the WD continued until 1943 when the cheaper WD Austerity 2-8-0 was introduced. Production for British domestic use continued until 1946.

60 were built by the LNER to Railway Executive Committee order between 1943 and 1945. These were considered LMS stock and numbered as such (LMS Nos 8500-59). These were loaned by the REC to the LNER. The LNER subsequently chose to build some of the design for themselves. These were classified by the LNER as class O6. 

None of the former LNER Class O6 engines were preserved. However, fourteen 8Fs are known to have survived with six LMS/BR locomotives being preserved in the UK; a seventh was used a spares donor. None of the pre-war 8Fs survived into preservation. Three members of the class have over the years been repatriated to the UK from Turkey, with one later sent to a museum in Israel. In addition, two Turkish Railway (TCDD) locomotives have been preserved in Turkey, and some more remain there in a derelict state. One locomotive has even survived in Iraq. Two more are also visible underwater on the wreck of the SS Thistlegorm. In addition, 1 LNER-built example (48518) survived, but was used as a parts donor for 1014 County of Glamorgan and 45551 The Unknown Warrior. It was consequently dismantled, and the frames were scrapped at Bury in mid-2013.