A number of very early Scottish railway companies were short-lived. Many were amalgamated into larger organisations, which were themselves grouped into two companies of the 'Big Four' which extended into Scotland in 1923 (see List of railway companies involved in the 1923 grouping). Some remained independent throughout their existence.

This is a sub-category of Category:Early British railway companies and Category:Railway lines in Scotland. See also the List of early British railway companies.