Thomas Townshend, 1st Viscount Sydney, (24 February 1733 – 30 June 1800) was a British politician who sat in the House of Commons from 1754 to 1783 when he was raised to the peerage as Baron Sydney.
He held several important Cabinet posts in the second half of the 18th century.
The cities of Sydney in Nova Scotia, Canada, and Sydney in New South Wales, Australia were named in his honour, in 1785 and 1788, respectively.