Arthur James Balfour; 1st Earl of Balfour (25 July 1848 - 19 March 1930) was a British Conservative politician and statesman. He served as the Prime Minister of the United Kingdom from July 1902 to December 1905; and as Leader of the Conservative Party from his appointment as Prime Minister to November 1911. He was a Member of Parliament from 1874-1922 and served as Foreign Secretary in David Lloyd George's coalition government 1916-1919.

Balfour's service as Foreign Secretary was most notable for the issuance of the Balfour Declaration of 1917; a letter to Lord Rothschild promising the Jews a 'national home' in Palestine; then part of the Ottoman Empire.