The Great Northern Railway (GNR) was a British railway company incorporated in 1846 with the object of building a line from London to York. It quickly saw that seizing control of territory was key to development, and it acquired, or took leases of, many local railways, whether actually built or not. In so doing, it overextended itself financially.

Nevertheless, it succeeded in reaching into the coalfields of Nottinghamshire, Derbyshire and Yorkshire, as well as establishing dominance in Lincolnshire and north London. Bringing coal south to London was dominant, but general agricultural business, and short- and long-distance passenger traffic, were important activities too. Its fast passenger express trains captured the public imagination, and its Chief Mechanical Engineer Nigel Gresley became a celebrity.

Anglo-Scottish travel on the East Coast Main Line became commercially important; the GNR controlled the line from London to Doncaster and allied itself with the North Eastern Railway and the North British Railway so as to offer seamless travel facilities.

The main line railways of Great Britain were "grouped" following the Railways Act 1921 into one or other of four new larger concerns. The Great Northern Railway was a constituent of the London and North Eastern Railway, which took control at the beginning of 1923. Although many local lines have been closed, much of the network is active today.