Appleby was a parliamentary constituency in the county of Westmorland in England. It existed for two separate periods: from 1295 to 1832, and from 1885 to 1918.

A rotten or pocket borough, also known as a nomination borough or proprietorial borough, was a parliamentary borough or constituency in England, Great Britain, or the United Kingdom before the Reform Act 1832, which had a very small electorate and could be used by a patron to gain unrepresentative influence within the unreformed House of Commons. The same terms were used for similar boroughs represented in the 18th-century Parliament of Ireland. The Reform Act 1832 abolished the majority of these rotten and pocket boroughs.