Sir Percy Alfred Harris, 1st Baronet PC (6 March 1876 – 28 June 1952) was a British Liberal Party politician. He was Liberal Chief Whip and Deputy Leader of the Liberal Parliamentary Party.
Sir Percy Harris was regarded as a radical Liberal with a strong social conscious which grew from representing a working class area of the East End of London. He was particularly interested in the issue of social housing, a major responsibility of the London County Council. He sided with H. H. Asquith against David Lloyd George from 1918 to 1923. Thereafter he sought unity within the Liberal Party. When the Liberal Party split in 1931 over the issue of Free Trade, he sided with Sir Herbert Samuel and against the Liberal National breakaway led by Sir John Simon. Under the leadership of Sir Archie Sinclair, he rose to prominence in the party. He was a strong supporter of the social policies advocated by Sir William Beveridge and was key to getting Beveridge to run for the Liberals.
Harris was born in Kensington, the second son of Wolf Harris (1833–1926) a Polish immigrant. He was educated at Harrow and Trinity Hall, Cambridge. Harris was called to the bar by Middle Temple in 1899. In 1901 he married Marguerite Frieda Bloxam (1877 – 1962). They had two sons including Jack Harris (23 July 1906 – 26 August 2009). A great-grandson is the former Liberal Democrat Member of Parliament Matthew Taylor — which Taylor, who was adopted, discovered in 2008.