Charles Spencer, 3rd Earl of Sunderland (23 April 1675 – 19 April 1722), known as Lord Spencer from 1688 to 1702, was an English statesman from the Spencer family. He served as Lord Lieutenant of Ireland (1714–1717), Lord Privy Seal (1715–1716), Lord President of the Council (1717–1719) and First Lord of the Treasury (1718–1721).
Having succeeded to the peerage in 1702, Sunderland was one of the commissioners for the union between England and Scotland, and in 1705, he was sent to Vienna as envoy extraordinary. Although he was tinged with republican ideas and had made himself obnoxious to Queen Anne by opposing the grant to her husband, Prince George, through the influence of Marlborough he was foisted into the ministry as Secretary of State for the Southern Department, taking office in December 1706. From 1708 to 1710, he was one of the five Whigs collectively called the Junto, who dominated the government, but he had many enemies, the Queen still disliked him, and in June 1710, he was dismissed. Anne offered him a pension of £3000 a year, but this he refused, saying "if he could not have the honour to serve his country he would not plunder it." When Marlborough protested about the dismissal, the Queen inquired sarcastically whether "the Peace of Europe must depend on it?" She added that Sunderland was universally unpopular, which was indeed the case.
Sunderland continued to take part in public life, and was active in communicating with the court of Hanover about the steps to be taken in view of the approaching death of the queen. He made the acquaintance of George I in 1706, but when the elector became king, Sunderland only secured the comparatively unimportant position of Lord Lieutenant of Ireland. In August 1715, he joined the cabinet as Lord Privy Seal. After a visit to George I in Hanover, he secured in April 1717 the position of Secretary of State for the Northern Department. This he retained until March 1718, when he became First Lord of the Treasury, holding also the post of Lord President of the Council. He was now effectively the prime minister. Sunderland was especially interested in the proposed peerage bill, a measure designed to limit the number of members of the House of Lords, but this was defeated owing partly to the opposition of Sir Robert Walpole. In 1719 he was one of the main subscribers in the Royal Academy of Music (1719), a corporation that produced baroque opera on stage.
The bursting of the South Sea Bubble led to his political ruin. He had taken some part in launching the scheme of 1720, therefore public opinion was roused against him and it was only through the efforts of Walpole that he was acquitted by the House of Commons, when the matter was investigated. In April 1721, he resigned his offices, but he retained his influence with George I until his death on 19 April 1722.
Sunderland inherited his father's passion for intrigue, while his manners were repelling, but he stands high among his associates for disinterestedness and had an alert and discerning mind. From his early years he had a great love of books, and he spent his leisure and his wealth in forming the library at Althorp, which in 1703 was described as "the finest in Europe." In 1749 part of it was removed to Blenheim Palace.
Sunderland's second wife died in April 1716, after a career of considerable influence on the political life of her time. In 1717, he married an Irish lady of fortune, Judith Tichborne (d. 1749), daughter of Sir Benjamin Tichborne (younger brother of Sir Henry Tichborne, 1st Baron Ferrard, Irish cr. 1715) and Elizabeth Gibbs. She later married Sir Robert Sutton.
In 1722 Sunderland was implicated in what became known as the Atterbury Plot, to restore the House of Stuart, and his death was one of the factors which brought the Plot to light.
The town of Sunderland, Massachusetts, was named in his honor in November of 1718, just after he became Lord President of the Council.