Sir Austen Chamberlain (1863 – 1937) was a British statesman and politician.

The son of Birmingham's Mayor Joseph Chamberlain and older half-brother of Neville Chamberlain, Austen was first elected to parliament in 1892. In 1903, he became Chancellor of the Exchequer, and following his father's stroke and enforced retirement from active politics a few years later, he became the leader of the protectionist wing of the Conservative Party.

In 1911, Chamberlain was one of the leading candidates to succeed Arthur James Balfour as Conservative leader, but due to a deadlock between protectionists and free traders, Andrew Bonar Law was chosen as a compromise candidate. In 1915 Chamberlain returned to the cabinet in Asquith's coalition government, as Secretary of State for India.

He continued as India Secretary in Lloyd George's government after 1916 but resigned in 1917. Later he returned to government and became a member of the War Cabinet in 1918. In 1919, he was again at the Exchequer. In 1921, Bonar Law retired, and Chamberlain succeeded him both as leader of Conservative MPs (but technically not of the Party as a whole, as is popularly supposed, since that accolade was then only given to a Conservative who became Prime Minister) and as Lord Privy Seal. Unfortunately for Chamberlain, in late 1922 the Conservative backbenchers rebelled against their leadership for remaining in the coalition with Lloyd George, and dumped Chamberlain as their leader, bringing Law back as Prime Minister. Chamberlain is often cited as being the only modern leader of the Conservative Party not to become Prime Minister until William Hague and Iain Duncan Smith, but this is technically inaccurate as he was not overall leader.

Chamberlain did, however, return to government in Stanley Baldwin's second government, serving in the important office of Secretary of State for Foreign Affairs from 1924 to 1929. As Foreign Secretary, Chamberlain negotiated the Locarno Pact of 1925 with Gustav Stresemann of Germany and Aristide Briand of France, for which he won the Nobel Peace Prize, and secured Britain's accession to the Kellogg-Briand Pact outlawing war. Chamberlain and his wife were rather sympathetic to fascist Italy, and Chamberlain famously said that Benito Mussolini was "a man with whom business could be done".

In 1931, Sir Austen returned briefly to government as First Lord of the Admiralty in Ramsay MacDonald's first National Government, but soon retired from government. Over the next six years as a senior backbencher he gave strong support to the National Government but was critical of their foreign policy. In 1935 the government faced a parliamentary rebellion over the Hoare-Laval Pact and Sir Austen believed was asked "to talk about the Foreign Secretaryship" - which he assumed to mean he would be offered the post if he supported the government and it survived. He did indeed support it but afterwards was merely asked his opinion of the suitability of his former Parliamentary Private Secretary Anthony Eden for the post. Winston Churchill claims in his memoirs that had this crisis ended differently Sir Austen may have been called upon as a respected statesman to form a government but this view is not widely supported.

Sir Austen lived until March 1937, dying just ten weeks before his half-brother Neville Chamberlain became Prime Minister.

|- style="text-align: center;" | width="30%" |Preceded by:
Charles Thomson Ritchie | width="40%" style="text-align: center;" |Chancellor of the Exchequer
1903–1905 | width="30%" |Succeeded by:
Herbert Henry Asquith

|- style="text-align: center;" | width="30%" |Preceded by:
The Earl of Crewe | width="40%" style="text-align: center;" |Secretary of State for India
1915–1917 | width="30%" |Succeeded by:
Edwin Samuel Montagu

|- style="text-align: center;" | width="30%" |Preceded by:
Andrew Bonar Law | width="40%" style="text-align: center;" |Chancellor of the Exchequer
1919–1921 | width="30%" |Succeeded by:
Sir Robert Horne

|- style="text-align: center;" | width="30%" |Preceded by:
Ramsay Macdonald | width="40%" style="text-align: center;" |Foreign Secretary
1924–1929 | width="30%" |Succeeded by:
Arthur Henderson

|- style="text-align: center;" | width="30%" |Preceded by:
A. V. Alexander | width="40%" style="text-align: center;" |First Lord of the Admiralty
1931 | width="30%" |Succeeded by:
The Viscount Monsell