Sir Walter Clarke Buchanan (20 June 1838 – 19 July 1924) was a New Zealand politician who became a member of the Reform Party that formed in 1909. Despite never being appointed as a minister, he was an influential politician and a strong advocate for farming interests.

Buchanan was born in 1838 in Kilmodan, Argyllshire, Scotland. He was the son of the farmer Donald McChananich and of his wife Janet Clarke. He was baptised under McChananich, the Gaelic version of Buchanan.^[1] He attended Greenock Academy,^[2] and moved to Australia at the age of 18, where he became a farmer. Around 1863 he moved to New Zealand.^[1]

Buchanan entered politics in 1881, representing first Wairarapa South from 1881 to 1887, and then Wairarapa from 1887 to 1899, 1902 to 1905 and 1908 to 1914. He was in Parliament for much of the next 33 years, losing three elections.^[3]

In the four general elections between 1881 and 1890, he always beat Henry Bunny,^[4][5][6][7] who had represented the Wairarapa electorate continuously since an 1865 by-election.^[3]

He lost Wairarapa to J. T. Marryat Hornsby, the frequent Liberal Party candidate for the electorate, in 1899, won it back in 1902, lost it in 1905 and won it back in 1908. He finally lost the seat to Hornsby in 1914.^[8]

In the House, he was a staunch conservative voice, and a diehard opponent of the Liberal government of Richard Seddon.

Buchanan was knighted in 1913^[3] and appointed to the Legislative Council in 1915, where he served until his death in 1924.^[9] Despite his long experience in politics, he was never appointed a Minister (partly because the Liberal Party was in power as from 1891 to 1914).^[3] Buchanan was appointed honorary colonel of the 17th (Ruahine) Regiment in 1916.^[10]

Buchanan died on 19 July 1924 of heart failure following a car crash. He had never married.^[1] He was buried at Clareville Cemetery, Carterton.^[11]