Frederick William Lambton, 4th Earl of Durham (19 June 1855 – 31 January 1929) was a British peer, a Liberal (and later Liberal Unionist) politician, and the son of George Lambton, 2nd Earl of Durham. He inherited the Earldom from his twin brother, John Lambton, 3rd Earl of Durham, when the latter died with no legitimate children.
He married Beatrix Bulteel (1859 – 27 April 1937), his second cousin once removed, on 26 May 1879). They had six children:
He was elected at the 1880 general election as a Liberal Member of Parliament (MP) for South Durham, 384 and held that seat until the constituency was abolished for the 1885 general election. He did not stand in 1885, but having joined the Liberal unionists in 1885 he unsuccessfully contested Berwick-Upon-Tweed in 1886,Sunderland in 1886, and a by-election in South East Durham in February 1898.
He was returned to the House of Commons after a fifteen-years absence at the 1900 general election, when he defeated Joseph Richardson, the Liberal winner of the 1898 by-election. Lambton was re-elected unopposed in 1906, but lost the seat by a wide margin to a Liberal candidate in January 1910.