Charles Watson-Wentworth, 2nd Marquess of Rockingham (May 13, 1730 – July 1, 1782) was a British politician, most notable for his two terms as Whig Prime Minister of Great Britain. He served in only two high offices during his lifetime (Prime Minister and Leader of the House of Lords), but was nonetheless very influential during his one and a half years of service.

A descendant of Thomas Wentworth, Charles was brought up at the family home of Wentworth Woodhouse near Rotherham in South Yorkshire. He was educated at the Westminster School and at St John's College, Cambridge. In 1746, he rode from Wentworth to Carlisle to join the Duke of Cumberland in pursuit of the "Young Pretender." Four years later, he was created Earl of Malton in the Peerage of Ireland, then acceded to his father's marquessate shortly thereafter.

He took his seat in the House of Lords the following year, and was given the Garter in 1761. In 1762, King George III appointed his friend and mentor, Lord Bute, to the position of Prime Minister; however, he was forced to resign due to growing opposition. He was replaced by George Grenville, who again did not attract enough support; following Grenville's resignation in 1765, Lord Rockingham was appointed Prime Minister.

Rockingham appointed his allies Henry Seymour Conway and the Duke of Grafton as secretaries of state. During his term of office, he repealed the Stamp Act, reducing the tax burden on the colonies. However, internal dissent within the cabinet led to his resignation and the appointment of Lord Chatham as Prime Minister (the Duke of Grafton was appointed First Lord of the Treasury, one of the few cases in which those two offices were separate).

Rockingham spent the next sixteen years in opposition. He was a keen supporter of constitutional rights for colonists, and backed the claim for American independence. In 1782 he was appointed Prime Minister for a second time (with Conway and Lord Shelburne as secretaries of state) and, upon taking office, acknowledged the independence of the United States, initiating an end to British involvement in the Revolutionary War. However, this term was short-lived, for Lord Rockingham died 14 weeks later. Rockingham County, New Hampshire and Rockingham County, Virginia in the United States are named in his honour.

Rockingham's First Government, July 1765 - July 1766

• Lord Rockingham - First Lord of the Treasury and Leader of the House of Lords
• The Earl of Northington - Lord Chancellor
• The Earl of Winchilsea - Lord President of the Council
• The Duke of Newcastle - Lord Privy Seal
• William Dowdeswell - Chancellor of the Exchequer
• The Duke of Grafton - Secretary of State for the Northern Department
• Henry Seymour Conway - Secretary of State for the Southern Department and Leader of the House of Commons
• Lord Granby - Master-General of the Ordnance
• The Earl of Egmont - First Lord of the Admiralty

Rockingham's Second Government, March - July 1782

• Lord Rockingham - First Lord of the Treasury, Leader of the House of Lords
• Lord Thurlow - Lord Chancellor
• Lord Camden - Lord President of the Council
• The Duke of Grafton - Lord Privy Seal
• Lord Shelburne - Secretary of State for the Home Department
• Charles James Fox - Secretary of State for Foreign Affairs and Leader of the House of Commons
• Lord Keppel - First Lord of the Admiralty
• Henry Seymour Conway - Commander in Chief of the Forces
• The Duke of Richmond - Master-General of the Ordnance
• Lord John Cavendish - Chancellor of the Exchequer
• Lord Ashburton - Chancellor of the Duchy of Lancaster

|- style="text-align: center;" | width="30%" |Preceded by:
Unknown | width="40%" style="text-align: center;" |Leader of the House of Lords
1765–1766 | width="30%" |Succeeded by:
The Duke of Grafton