David Garro Trefgarne, 2nd Baron Trefgarne, PC (born 31 March 1941), is a British Conservative politician.

In contrast to his father, who was a Liberal and later Labour politician, he chose to sit on the Conservative benches.

Trefgarne was an opposition Whip from 1977 to 1979 and then served in the Conservative administration of Margaret Thatcher as a Government Whip from 1979 to 1981 and as Parliamentary Under-Secretary of State at the Department of Trade in 1981, at the Foreign and Commonwealth Office from 1981 to 1982, at the Department of Health and Social Security from 1982 to 1983 and at the Ministry of Defence from 1983 to 1985.

The latter year he was promoted to Minister of State for Defence Support, a post he held until 1986, and then served as Minister of State for Defence Procurement from 1986 to 1989 and as a Minister of State at the Department of Trade and Industry from 1989 to 1990.

According to the Electoral Reform Society, he has since blocked further reform of the Lords, tabling 'wrecking' amendments to a draft Bill to abolish by-elections for hereditary peers, proposed by Lord Grocott in 2018.