Thomas Townshend, 1st Viscount Sydney (24 February 1732 - 30 June 1800), the British politician after whom the city of Sydney, Australia, is named, was born at Frognal House, near Chislehurst in Kent. He was educated at Clare College, Cambridge University. Townshend was elected to the House of Commons in 1754 as Whig member for Whitchurch and held that seat till his elevation to the peerage. He initially aligned himself with his great uncle Thomas Pelham-Holles, 1st Duke of Newcastle but later joined William Pitt the Elder in opposition to William Wyndham Grenville, 1st Lord Grenville.

Townshend was a lord of the treasury in the first Rockingham ministry and continued in that office in the Pitt (now Lord Chatham) administration until December 1767, when he became a member of the Privy Council and joint Paymaster-General. During the ministry of Lord Chatham and Lord Grafton he supported the American revenue program initiated by his cousin, Charles Townshend, but was forced out of office in June, 1768.

Townshend remained in opposition until the end of Lord North's ministry and spoke frequently in the House of Commons against the American war. Although he had no close party connection, he was inclined toward the Chathamites. He took office again as secretary at war in the second Rockingham ministry. When the 2nd Earl of Shelburne became prime minister in July 1782, Townshend succeeded him as Secretary of State for the Home Department and Leader of the House of Commons. He was created Baron Sydney and entered the House of Lords in 1783. He took the title Sydney to commemorate his descent from Robert Sydney, 2nd Earl of Leicester, who traced his descent from a Surrey yeoman, John de Sydenie. The name Sydney derives from a village in Normandy called Saint-Denis, presumably named for St Denis, the patron saint of France. St Denis, or Dionysius, the first bishop of Paris, was martyred in AD 270.

He opposed the Fox-North coalition and returned to political office with Pitt, serving as Home Secretary from 1783 to 1789. Following the loss of the North colonies, Townshend, as Home Secretary in the Pitt Government, was given responsibility for devising a plan to settle convicts at Botany Bay. His choice of Arthur Phillip as Governor was inspired and Phillip's leadership was instrumental in ensuring the penal colony survived the early years of struggle and famine. On 22 January 1788, Phillip named Sydney Cove in honour of Townshend and the settlement became known as Sydney Town. In 1789 he was created Viscount Sydney.

Sydney's reputation has suffered at the hands of the nationalist school of Australian historians, such as Manning Clark. In his influential A History of Australia (Melbourne University Press 1961) Clark wrote: "Mr Thomas Townshend, commonly denominated Tommy Townshend, owed his political career to a very independent fortune and a considerable parliamentary interest, which contributed to his personal no less than his political elevation, for his abilities, though respectable, scarcely rose above mediocrity." Other writers have portrayed Sydney as a cruel monster for dispatching the unfortunate convicts to the far side of the earth.

In fact, Townshend was, by the standards of his time, an enlightened and progressive politician. He supported the American Revolution and the development of Canada. The city of Sydney in Nova Scotia is named after him in memory of his efforts on behalf of the loyalist settlers of Canada.

More recently Townshend's reputation has been revisited by Australian historians. Alan Atkinson wrote in The Europeans in Australia (Oxford University Pressm 1997): "Townshend was an anomaly in the British Cabinet, and his ideas were in some ways old-fashioned... He had long been interested in the way in which the empire might be a medium for British liberties, traditionally understood." He took the view that convicts should be given the chance to redeem themselves through self-government in penal colonies such as New South Wales. Governor Phillip's well-known statement that "There will no slavery in a new country and hence no slaves" is an accurate reflection of Townshend's philosophy.

Sydney's papers are held by the William L. Clements Library at the University of Michigan.

{| border="2" align="center" |- |width="30%" align="center"|Preceded by:
New Creation |width="40%" align="center"|Viscount Sydney |width="30%" align="center" rowspan="2"|Followed by:
John Thomas Sydney |}