Robert Adam Philips Haldane Haldane-Duncan, 3rd Earl of Camperdown (28 May 1841 – 5 June 1918), styled Viscount Duncan from 1859 to 1867, was a British Liberal politician.

His sister was Julia Janet Georgiana Haldane-Duncan, a notable artist and Lady of the Bedchamber to Queen Victoria who married George Abercromby, 4th Baron Abercromby.

[1] His younger brother was George Haldane-Duncan, 4th Earl of Camperdown.

[1] He succeeded his father in the earldom in 1867 and took his seat on the Liberal benches in the House of Lords.

The following year he was appointed a Lord-in-waiting (government whip in the House of Lords) in William Ewart Gladstone's first administration, a post he held until 1870, and then served as a Civil Lord of the Admiralty from 1870 to 1874.