David George Hamilton Frost, Baron Frost CMG PC (born 21 February 1965) is a former British diplomat, civil servant and politician who served as a Minister of State at the Cabinet Office between March and December 2021. Frost was Chief Negotiator of Task Force Europe from January 2020 until his resignation in December 2021.

Frost spent his early professional career in the Foreign and Commonwealth Office (FCO), becoming Ambassador to Denmark, EU Director at the FCO, and Director for Europe and International Trade at the Department for Business, Innovation and Skills. He was a special adviser to Boris Johnson when the latter was Foreign Secretary in Theresa May's government.

After Johnson was appointed prime minister, Frost was Chief Negotiator for Exiting the European Union from 2019 to 2020 and the Prime Minister's Europe Adviser from 2019 to 2021. He was appointed Chief Negotiator of Task Force Europe in January 2020. He was elevated to the House of Lords as a life peer in September 2020. Frost became Minister of State at the Cabinet Office and a full member of the cabinet in March 2021. He resigned from his government positions in December 2021.

Frost was born in Derby and was educated at Nottingham High School as a free scholar from 1976 to 1983, before attending St. John's College, Oxford, where he took a first-class degree (MA) in French and history.

Frost joined the Foreign and Commonwealth Office (FCO) in 1987, and shortly after was posted to the British High Commission in Nicosia where he learned Greek and was responsible for covering Greek Cypriot politics and the Cyprus problem. In 1993, he was posted to the UK Representation to the EU in Brussels as First Secretary for Economic and Financial Affairs, where he worked on issues such as the EU Budget, the economic and financial implications of enlargement to Central Europe, and the Euro. He was then posted to the UK Mission to the United Nations in New York, where he covered Human Rights and Social and Economic Affairs.

Frost returned to London to be successively the Private Secretary to the Head of the Diplomatic Service, Sir John Kerr (now Lord Kerr of Kinlochard), and Deputy Head of the European Union External Department, covering international trade policy issues and relations with the Balkans and Eastern Europe.

Frost was promoted Economic Counsellor to the British Embassy, Paris, in 2001, where he was responsible for reporting and lobbying on all aspects of French economic and commercial life, together with its EU policy. He returned to London to be Head of the EU (Internal) Department and then Director for the European Union in the Foreign Office. In this period he led work on a range of economic and social issues, notably the resistance to the initial Working Time Directive, and the negotiation on the EU's multi-annual Budget framework. He was a member of the UK's leadership team during its EU Presidency in 2005.

From May 2006 until October 2008, Frost served as HM Ambassador to Denmark and was appointed Companion of the Order of St Michael and St George in the 2006 Birthday Honours. He was then Director for Strategy and Policy Planning in the Foreign Office from October 2008 to October 2010, before being seconded to the Department for Business, Innovation and Skills where he served three years as Director for Europe, Trade, and International Affairs, HMG's most senior trade policy official.