Welbore Ellis, 1st Baron Mendip, PC, FRS (15 December 1713 – 2 February 1802) was an English politician who sat in the House of Commons for 53 years from 1741 to 1794 when he was raised to the peerage as Baron Mendip.

He held a number of political offices, including briefly serving as Secretary for the Colonies in 1782 during the American War of Independence.

[1] In 1762, he succeeded Charles Townshend as Secretary at War, and in 1763, he proposed the appropriation of twenty army regiments to the colonies of America.

In 1738 he inherited a large fortune from his uncle, John Ellis and built Clifden House in Brentford.

Ellis nevertheless died childless in February 1802, aged 88, and was succeeded in the barony according to the special remainder by his great-nephew, Henry Welbore Agar, 2nd Viscount Clifden, who assumed the surname of Ellis two years later.