Sir Edward Thornton, 2nd Count of Cacilhas, GCB, PC (13 July 1817 – 26 January 1906) was a British diplomat who held posts in Latin America, the Ottoman Empire, the Russian Empire, and served for fourteen years as Minister to the United States.

He was the eldest son of Sir Edward Thornton, 1st Count of Cacilhas, also a diplomat, who for many years held the post of British Minister to Portugal.

[1][2][3] He entered the diplomatic service as attaché to the mission at Turin in the Kingdom of Sardinia in 1842, filled the same position in Mexico in 1845, and was made Secretary of Legation in that Capital in 1853.

[1] Thornton's diplomacy was praised in a House of Commons debate on the Christie Question, William "Seymour" Vesey-FitzGerald calling him "a gentleman who knows how to conciliate... [he knows] that it is not his duty to 'read lessons' to foreign Governments", his behaviour being contrasted with that of William Dougal Christie, British consul in Brazil.

[9][10] Thornton's lengthiest assignment was as Minister to the United States, a position he held for fourteen years (1867–1881).

[1][3] Subsequent to his retirement from the diplomatic service, Thornton was able to supplement his pension income by accepting various offers of company directorships and like offices.

When an aggrieved subscriber to The Globe Venture Syndicate float took legal action arguing that there were fraudulent misrepresentations in the prospectus, Thornton was required to undergo cross-examination in the Chancery Division of the High Court.

The following day Thornton`s counsel informed the court that "after the evidence which had been given, he did not think he could resist judgment against Sir Edward Thornton for £2000 ..."[23][24] In June 1900 a winding-up order was made against the Globe Venture Syndicate, and in February 1901 a public inquiry was held in the London Bankruptcy Court into the failure of the company.

[25] In 1854, Thornton married Mary Jane (née Maitland) Melville (1827–1907), at St Peter's Church, Eaton Square.

[27] Together, they were the parents of:[28] After a lengthy illness, Thornton died at his London residence, 5 Tedworth Square, on 26 January 1906.