Lord Richard Frederick Cavendish, CB, CMG, DL, JP (31 January 1871 – 7 January 1946), known as Richard Cavendish until 1908, was a British , author, magistrate, and politician.
A prominent figure in the House of Cavendish, he was a younger son of Lord Edward Cavendish, third son of the 7th Duke of Devonshire. The 8th Duke of Devonshire was his uncle and the 9th Duke of Devonshire his elder brother. His mother was Emma Elizabeth, daughter of the Hon. William Lascelles. He was educated at Eton and Trinity College, Cambridge, where he was a member of the Pitt Club.
Cavendish was elected in the 1895 general election as the Member of Parliament (MP) for North Lonsdale. He crossed the floor from being a supporter of the Liberal Unionists to being a member of the Liberal Party in 1904. Therefore, he was one of the few Liberal MPs who lost their seat in the 1906 election. In December 1908 he was appointed chairman of the Royal Commission on Systems of Election, with the mandate "to secure a fully representative character for popularly elected legislative bodies" and "to consider whether, and how far, they, or any of them, are capable of application in this country in regard to the existing electorate". The commission reported in 1910, recommending the abolition of two member constituencies "as soon as possible"; this was implemented. The commission also recommended the adoption of an alternative vote system, which was not implemented.